langchain-exa

Reference docs

This page contains reference documentation for Exa. See the docs for conceptual guides, tutorials, and examples on using Exa modules.

langchain_exa

LangChain integration for Exa.

ExaSearchRetriever

Bases: BaseRetriever

Exa Search retriever.

METHOD	DESCRIPTION
get_name	Get the name of the Runnable.
get_input_schema	Get a Pydantic model that can be used to validate input to the Runnable.
get_input_jsonschema	Get a JSON schema that represents the input to the Runnable.
get_output_schema	Get a Pydantic model that can be used to validate output to the Runnable.
get_output_jsonschema	Get a JSON schema that represents the output of the Runnable.
config_schema	The type of config this Runnable accepts specified as a Pydantic model.
get_config_jsonschema	Get a JSON schema that represents the config of the Runnable.
get_graph	Return a graph representation of this Runnable.
get_prompts	Return a list of prompts used by this Runnable.
__or__	Runnable "or" operator.
__ror__	Runnable "reverse-or" operator.
pipe	Pipe Runnable objects.
pick	Pick keys from the output dict of this Runnable.
assign	Assigns new fields to the dict output of this Runnable.
invoke	Invoke the retriever to get relevant documents.
ainvoke	Asynchronously invoke the retriever to get relevant documents.
batch	Default implementation runs invoke in parallel using a thread pool executor.
batch_as_completed	Run invoke in parallel on a list of inputs.
abatch	Default implementation runs ainvoke in parallel using asyncio.gather.
abatch_as_completed	Run ainvoke in parallel on a list of inputs.
stream	Default implementation of stream, which calls invoke.
astream	Default implementation of astream, which calls ainvoke.
astream_log	Stream all output from a Runnable, as reported to the callback system.
astream_events	Generate a stream of events.
transform	Transform inputs to outputs.
atransform	Transform inputs to outputs.
bind	Bind arguments to a Runnable, returning a new Runnable.
with_config	Bind config to a Runnable, returning a new Runnable.
with_listeners	Bind lifecycle listeners to a Runnable, returning a new Runnable.
with_alisteners	Bind async lifecycle listeners to a Runnable.
with_types	Bind input and output types to a Runnable, returning a new Runnable.
with_retry	Create a new Runnable that retries the original Runnable on exceptions.
map	Return a new Runnable that maps a list of inputs to a list of outputs.
with_fallbacks	Add fallbacks to a Runnable, returning a new Runnable.
as_tool	Create a BaseTool from a Runnable.
__init__
is_lc_serializable	Is this class serializable?
get_lc_namespace	Get the namespace of the LangChain object.
lc_id	Return a unique identifier for this class for serialization purposes.
to_json	Serialize the Runnable to JSON.
to_json_not_implemented	Serialize a "not implemented" object.
configurable_fields	Configure particular Runnable fields at runtime.
configurable_alternatives	Configure alternatives for Runnable objects that can be set at runtime.
validate_environment	Validate the environment.

name class-attribute instance-attribute

name: str | None = None

The name of the Runnable. Used for debugging and tracing.

InputType property

InputType: type[Input]

Input type.

The type of input this Runnable accepts specified as a type annotation.

RAISES	DESCRIPTION
TypeError	If the input type cannot be inferred.

OutputType property

OutputType: type[Output]

Output Type.

The type of output this Runnable produces specified as a type annotation.

RAISES	DESCRIPTION
TypeError	If the output type cannot be inferred.

input_schema property

input_schema: type[BaseModel]

The type of input this Runnable accepts specified as a Pydantic model.

output_schema property

output_schema: type[BaseModel]

Output schema.

The type of output this Runnable produces specified as a Pydantic model.

config_specs property

config_specs: list[ConfigurableFieldSpec]

List configurable fields for this Runnable.

lc_secrets property

lc_secrets: dict[str, str]

A map of constructor argument names to secret ids.

For example, {"openai_api_key": "OPENAI_API_KEY"}

lc_attributes property

lc_attributes: dict

List of attribute names that should be included in the serialized kwargs.

These attributes must be accepted by the constructor.

Default is an empty dictionary.

tags class-attribute instance-attribute

tags: list[str] | None = None

Optional list of tags associated with the retriever.

These tags will be associated with each call to this retriever, and passed as arguments to the handlers defined in callbacks.

You can use these to eg identify a specific instance of a retriever with its use case.

metadata class-attribute instance-attribute

metadata: dict[str, Any] | None = None

Optional metadata associated with the retriever.

This metadata will be associated with each call to this retriever, and passed as arguments to the handlers defined in callbacks.

You can use these to eg identify a specific instance of a retriever with its use case.

k class-attribute instance-attribute

k: int = 10

The number of search results to return (1 to 100).

include_domains class-attribute instance-attribute

include_domains: list[str] | None = None

A list of domains to include in the search.

exclude_domains class-attribute instance-attribute

exclude_domains: list[str] | None = None

A list of domains to exclude from the search.

start_crawl_date class-attribute instance-attribute

start_crawl_date: str | None = None

The start date for the crawl (in YYYY-MM-DD format).

end_crawl_date class-attribute instance-attribute

end_crawl_date: str | None = None

The end date for the crawl (in YYYY-MM-DD format).

start_published_date class-attribute instance-attribute

start_published_date: str | None = None

The start date for when the document was published (in YYYY-MM-DD format).

end_published_date class-attribute instance-attribute

end_published_date: str | None = None

The end date for when the document was published (in YYYY-MM-DD format).

use_autoprompt class-attribute instance-attribute

use_autoprompt: bool | None = None

Whether to use autoprompt for the search.

type class-attribute instance-attribute

type: str = 'neural'

The type of search, 'keyword', 'neural', or 'auto'. Default: neural

highlights class-attribute instance-attribute

highlights: HighlightsContentsOptions | bool | None = None

Whether to set the page content to the highlights of the results.

text_contents_options class-attribute instance-attribute

text_contents_options: TextContentsOptions | dict[str, Any] | Literal[True] = True

How to set the page content of the results. Can be True or a dict with options like max_characters.

livecrawl class-attribute instance-attribute

livecrawl: Literal['always', 'fallback', 'never'] | None = None

Option to crawl live webpages if content is not in the index. Options: "always", "fallback", "never".

summary class-attribute instance-attribute

summary: bool | dict[str, str] | None = None

Whether to include a summary of the content. Can be a boolean or a dict with a custom query.

get_name

get_name(suffix: str | None = None, *, name: str | None = None) -> str

Get the name of the Runnable.

PARAMETER	DESCRIPTION
suffix	An optional suffix to append to the name. TYPE: str | None DEFAULT: None
name	An optional name to use instead of the Runnable's name. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
str	The name of the Runnable.

get_input_schema

get_input_schema(config: RunnableConfig | None = None) -> type[BaseModel]

Get a Pydantic model that can be used to validate input to the Runnable.

Runnable objects that leverage the configurable_fields and configurable_alternatives methods will have a dynamic input schema that depends on which configuration the Runnable is invoked with.

This method allows to get an input schema for a specific configuration.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	A Pydantic model that can be used to validate input.

get_input_jsonschema

get_input_jsonschema(config: RunnableConfig | None = None) -> dict[str, Any]

Get a JSON schema that represents the input to the Runnable.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the input to the Runnable.

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


runnable = RunnableLambda(add_one)

print(runnable.get_input_jsonschema())

Added in langchain-core 0.3.0

get_output_schema

get_output_schema(config: RunnableConfig | None = None) -> type[BaseModel]

Get a Pydantic model that can be used to validate output to the Runnable.

Runnable objects that leverage the configurable_fields and configurable_alternatives methods will have a dynamic output schema that depends on which configuration the Runnable is invoked with.

This method allows to get an output schema for a specific configuration.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	A Pydantic model that can be used to validate output.

get_output_jsonschema

get_output_jsonschema(config: RunnableConfig | None = None) -> dict[str, Any]

Get a JSON schema that represents the output of the Runnable.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the output of the Runnable.

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


runnable = RunnableLambda(add_one)

print(runnable.get_output_jsonschema())

Added in langchain-core 0.3.0

config_schema

config_schema(*, include: Sequence[str] | None = None) -> type[BaseModel]

The type of config this Runnable accepts specified as a Pydantic model.

To mark a field as configurable, see the configurable_fields and configurable_alternatives methods.

PARAMETER	DESCRIPTION
include	A list of fields to include in the config schema. TYPE: Sequence[str] | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	A Pydantic model that can be used to validate config.

get_config_jsonschema

get_config_jsonschema(*, include: Sequence[str] | None = None) -> dict[str, Any]

Get a JSON schema that represents the config of the Runnable.

PARAMETER	DESCRIPTION
include	A list of fields to include in the config schema. TYPE: Sequence[str] | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the config of the Runnable.

Added in langchain-core 0.3.0

get_graph

get_graph(config: RunnableConfig | None = None) -> Graph

Return a graph representation of this Runnable.

get_prompts

get_prompts(config: RunnableConfig | None = None) -> list[BasePromptTemplate]

Return a list of prompts used by this Runnable.

__or__

__or__(
    other: Runnable[Any, Other]
    | Callable[[Iterator[Any]], Iterator[Other]]
    | Callable[[AsyncIterator[Any]], AsyncIterator[Other]]
    | Callable[[Any], Other]
    | Mapping[str, Runnable[Any, Other] | Callable[[Any], Other] | Any],
) -> RunnableSerializable[Input, Other]

Runnable "or" operator.

Compose this Runnable with another object to create a RunnableSequence.

PARAMETER	DESCRIPTION
other	Another Runnable or a Runnable-like object. TYPE: Runnable[Any, Other] | Callable[[Iterator[Any]], Iterator[Other]] | Callable[[AsyncIterator[Any]], AsyncIterator[Other]] | Callable[[Any], Other] | Mapping[str, Runnable[Any, Other] | Callable[[Any], Other] | Any]

RETURNS	DESCRIPTION
RunnableSerializable[Input, Other]	A new Runnable.

__ror__

__ror__(
    other: Runnable[Other, Any]
    | Callable[[Iterator[Other]], Iterator[Any]]
    | Callable[[AsyncIterator[Other]], AsyncIterator[Any]]
    | Callable[[Other], Any]
    | Mapping[str, Runnable[Other, Any] | Callable[[Other], Any] | Any],
) -> RunnableSerializable[Other, Output]

Runnable "reverse-or" operator.

Compose this Runnable with another object to create a RunnableSequence.

PARAMETER	DESCRIPTION
other	Another Runnable or a Runnable-like object. TYPE: Runnable[Other, Any] | Callable[[Iterator[Other]], Iterator[Any]] | Callable[[AsyncIterator[Other]], AsyncIterator[Any]] | Callable[[Other], Any] | Mapping[str, Runnable[Other, Any] | Callable[[Other], Any] | Any]

RETURNS	DESCRIPTION
RunnableSerializable[Other, Output]	A new Runnable.

pipe

pipe(
    *others: Runnable[Any, Other] | Callable[[Any], Other], name: str | None = None
) -> RunnableSerializable[Input, Other]

Pipe Runnable objects.

Compose this Runnable with Runnable-like objects to make a RunnableSequence.

Equivalent to RunnableSequence(self, *others) or self | others[0] | ...

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


def mul_two(x: int) -> int:
    return x * 2


runnable_1 = RunnableLambda(add_one)
runnable_2 = RunnableLambda(mul_two)
sequence = runnable_1.pipe(runnable_2)
# Or equivalently:
# sequence = runnable_1 | runnable_2
# sequence = RunnableSequence(first=runnable_1, last=runnable_2)
sequence.invoke(1)
await sequence.ainvoke(1)
# -> 4

sequence.batch([1, 2, 3])
await sequence.abatch([1, 2, 3])
# -> [4, 6, 8]

PARAMETER	DESCRIPTION
*others	Other Runnable or Runnable-like objects to compose TYPE: Runnable[Any, Other] | Callable[[Any], Other] DEFAULT: ()
name	An optional name for the resulting RunnableSequence. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableSerializable[Input, Other]	A new Runnable.

pick

pick(keys: str | list[str]) -> RunnableSerializable[Any, Any]

Pick keys from the output dict of this Runnable.

Pick a single key:

import json

from langchain_core.runnables import RunnableLambda, RunnableMap

as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)
chain = RunnableMap(str=as_str, json=as_json)

chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3]}

json_only_chain = chain.pick("json")
json_only_chain.invoke("[1, 2, 3]")
# -> [1, 2, 3]

Pick a list of keys:

from typing import Any

import json

from langchain_core.runnables import RunnableLambda, RunnableMap

as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)


def as_bytes(x: Any) -> bytes:
    return bytes(x, "utf-8")


chain = RunnableMap(str=as_str, json=as_json, bytes=RunnableLambda(as_bytes))

chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3], "bytes": b"[1, 2, 3]"}

json_and_bytes_chain = chain.pick(["json", "bytes"])
json_and_bytes_chain.invoke("[1, 2, 3]")
# -> {"json": [1, 2, 3], "bytes": b"[1, 2, 3]"}

PARAMETER	DESCRIPTION
keys	A key or list of keys to pick from the output dict. TYPE: str | list[str]

RETURNS	DESCRIPTION
RunnableSerializable[Any, Any]	a new Runnable.

assign

assign(
    **kwargs: Runnable[dict[str, Any], Any]
    | Callable[[dict[str, Any]], Any]
    | Mapping[str, Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any]],
) -> RunnableSerializable[Any, Any]

Assigns new fields to the dict output of this Runnable.

from langchain_core.language_models.fake import FakeStreamingListLLM
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import SystemMessagePromptTemplate
from langchain_core.runnables import Runnable
from operator import itemgetter

prompt = (
    SystemMessagePromptTemplate.from_template("You are a nice assistant.")
    + "{question}"
)
model = FakeStreamingListLLM(responses=["foo-lish"])

chain: Runnable = prompt | model | {"str": StrOutputParser()}

chain_with_assign = chain.assign(hello=itemgetter("str") | model)

print(chain_with_assign.input_schema.model_json_schema())
# {'title': 'PromptInput', 'type': 'object', 'properties':
{'question': {'title': 'Question', 'type': 'string'}}}
print(chain_with_assign.output_schema.model_json_schema())
# {'title': 'RunnableSequenceOutput', 'type': 'object', 'properties':
{'str': {'title': 'Str',
'type': 'string'}, 'hello': {'title': 'Hello', 'type': 'string'}}}

PARAMETER	DESCRIPTION
**kwargs	A mapping of keys to Runnable or Runnable-like objects that will be invoked with the entire output dict of this Runnable. TYPE: Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any] | Mapping[str, Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any]] DEFAULT: {}

RETURNS	DESCRIPTION
RunnableSerializable[Any, Any]	A new Runnable.

invoke

invoke(
    input: str, config: RunnableConfig | None = None, **kwargs: Any
) -> list[Document]

Invoke the retriever to get relevant documents.

Main entry point for synchronous retriever invocations.

PARAMETER	DESCRIPTION
input	The query string. TYPE: str
config	Configuration for the retriever. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional arguments to pass to the retriever. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
list[Document]	List of relevant documents.

Examples:

retriever.invoke("query")

ainvoke async

ainvoke(
    input: str, config: RunnableConfig | None = None, **kwargs: Any
) -> list[Document]

Asynchronously invoke the retriever to get relevant documents.

Main entry point for asynchronous retriever invocations.

PARAMETER	DESCRIPTION
input	The query string. TYPE: str
config	Configuration for the retriever. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional arguments to pass to the retriever. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
list[Document]	List of relevant documents.

Examples:

await retriever.ainvoke("query")

batch

batch(
    inputs: list[Input],
    config: RunnableConfig | list[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> list[Output]

Default implementation runs invoke in parallel using a thread pool executor.

The default implementation of batch works well for IO bound runnables.

Subclasses must override this method if they can batch more efficiently; e.g., if the underlying Runnable uses an API which supports a batch mode.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: list[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | list[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

RETURNS	DESCRIPTION
list[Output]	A list of outputs from the Runnable.

batch_as_completed

batch_as_completed(
    inputs: Sequence[Input],
    config: RunnableConfig | Sequence[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> Iterator[tuple[int, Output | Exception]]

Run invoke in parallel on a list of inputs.

Yields results as they complete.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: Sequence[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | Sequence[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
tuple[int, Output | Exception]	Tuples of the index of the input and the output from the Runnable.

abatch async

abatch(
    inputs: list[Input],
    config: RunnableConfig | list[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> list[Output]

Default implementation runs ainvoke in parallel using asyncio.gather.

The default implementation of batch works well for IO bound runnables.

Subclasses must override this method if they can batch more efficiently; e.g., if the underlying Runnable uses an API which supports a batch mode.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: list[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | list[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

RETURNS	DESCRIPTION
list[Output]	A list of outputs from the Runnable.

abatch_as_completed async

abatch_as_completed(
    inputs: Sequence[Input],
    config: RunnableConfig | Sequence[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> AsyncIterator[tuple[int, Output | Exception]]

Run ainvoke in parallel on a list of inputs.

Yields results as they complete.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: Sequence[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | Sequence[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[tuple[int, Output | Exception]]	A tuple of the index of the input and the output from the Runnable.

stream

stream(
    input: Input, config: RunnableConfig | None = None, **kwargs: Any | None
) -> Iterator[Output]

Default implementation of stream, which calls invoke.

Subclasses must override this method if they support streaming output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
Output	The output of the Runnable.

astream async

astream(
    input: Input, config: RunnableConfig | None = None, **kwargs: Any | None
) -> AsyncIterator[Output]

Default implementation of astream, which calls ainvoke.

Subclasses must override this method if they support streaming output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[Output]	The output of the Runnable.

astream_log async

astream_log(
    input: Any,
    config: RunnableConfig | None = None,
    *,
    diff: bool = True,
    with_streamed_output_list: bool = True,
    include_names: Sequence[str] | None = None,
    include_types: Sequence[str] | None = None,
    include_tags: Sequence[str] | None = None,
    exclude_names: Sequence[str] | None = None,
    exclude_types: Sequence[str] | None = None,
    exclude_tags: Sequence[str] | None = None,
    **kwargs: Any,
) -> AsyncIterator[RunLogPatch] | AsyncIterator[RunLog]

Stream all output from a Runnable, as reported to the callback system.

This includes all inner runs of LLMs, Retrievers, Tools, etc.

Output is streamed as Log objects, which include a list of Jsonpatch ops that describe how the state of the run has changed in each step, and the final state of the run.

The Jsonpatch ops can be applied in order to construct state.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Any
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
diff	Whether to yield diffs between each step or the current state. TYPE: bool DEFAULT: True
with_streamed_output_list	Whether to yield the streamed_output list. TYPE: bool DEFAULT: True
include_names	Only include logs with these names. TYPE: Sequence[str] | None DEFAULT: None
include_types	Only include logs with these types. TYPE: Sequence[str] | None DEFAULT: None
include_tags	Only include logs with these tags. TYPE: Sequence[str] | None DEFAULT: None
exclude_names	Exclude logs with these names. TYPE: Sequence[str] | None DEFAULT: None
exclude_types	Exclude logs with these types. TYPE: Sequence[str] | None DEFAULT: None
exclude_tags	Exclude logs with these tags. TYPE: Sequence[str] | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[RunLogPatch] | AsyncIterator[RunLog]	A RunLogPatch or RunLog object.

astream_events async

astream_events(
    input: Any,
    config: RunnableConfig | None = None,
    *,
    version: Literal["v1", "v2"] = "v2",
    include_names: Sequence[str] | None = None,
    include_types: Sequence[str] | None = None,
    include_tags: Sequence[str] | None = None,
    exclude_names: Sequence[str] | None = None,
    exclude_types: Sequence[str] | None = None,
    exclude_tags: Sequence[str] | None = None,
    **kwargs: Any,
) -> AsyncIterator[StreamEvent]

Generate a stream of events.

Use to create an iterator over StreamEvent that provide real-time information about the progress of the Runnable, including StreamEvent from intermediate results.

A StreamEvent is a dictionary with the following schema:

• event: Event names are of the format: on_[runnable_type]_(start|stream|end).
• name: The name of the Runnable that generated the event.
• run_id: Randomly generated ID associated with the given execution of the Runnable that emitted the event. A child Runnable that gets invoked as part of the execution of a parent Runnable is assigned its own unique ID.
• parent_ids: The IDs of the parent runnables that generated the event. The root Runnable will have an empty list. The order of the parent IDs is from the root to the immediate parent. Only available for v2 version of the API. The v1 version of the API will return an empty list.
• tags: The tags of the Runnable that generated the event.
• metadata: The metadata of the Runnable that generated the event.
• data: The data associated with the event. The contents of this field depend on the type of event. See the table below for more details.

Below is a table that illustrates some events that might be emitted by various chains. Metadata fields have been omitted from the table for brevity. Chain definitions have been included after the table.

Note

This reference table is for the v2 version of the schema.

event	name	chunk	input	output
on_chat_model_start	'[model name]'		{"messages": [[SystemMessage, HumanMessage]]}
on_chat_model_stream	'[model name]'	AIMessageChunk(content="hello")
on_chat_model_end	'[model name]'		{"messages": [[SystemMessage, HumanMessage]]}	AIMessageChunk(content="hello world")
on_llm_start	'[model name]'		{'input': 'hello'}
on_llm_stream	'[model name]'	'Hello'
on_llm_end	'[model name]'		'Hello human!'
on_chain_start	'format_docs'
on_chain_stream	'format_docs'	'hello world!, goodbye world!'
on_chain_end	'format_docs'		[Document(...)]	'hello world!, goodbye world!'
on_tool_start	'some_tool'		{"x": 1, "y": "2"}
on_tool_end	'some_tool'			{"x": 1, "y": "2"}
on_retriever_start	'[retriever name]'		{"query": "hello"}
on_retriever_end	'[retriever name]'		{"query": "hello"}	[Document(...), ..]
on_prompt_start	'[template_name]'		{"question": "hello"}
on_prompt_end	'[template_name]'		{"question": "hello"}	ChatPromptValue(messages: [SystemMessage, ...])

In addition to the standard events, users can also dispatch custom events (see example below).

Custom events will be only be surfaced with in the v2 version of the API!

A custom event has following format:

Attribute	Type	Description
name	str	A user defined name for the event.
data	Any	The data associated with the event. This can be anything, though we suggest making it JSON serializable.

Here are declarations associated with the standard events shown above:

format_docs:

def format_docs(docs: list[Document]) -> str:
    '''Format the docs.'''
    return ", ".join([doc.page_content for doc in docs])


format_docs = RunnableLambda(format_docs)

some_tool:

@tool
def some_tool(x: int, y: str) -> dict:
    '''Some_tool.'''
    return {"x": x, "y": y}

prompt:

template = ChatPromptTemplate.from_messages(
    [
        ("system", "You are Cat Agent 007"),
        ("human", "{question}"),
    ]
).with_config({"run_name": "my_template", "tags": ["my_template"]})

For instance:

from langchain_core.runnables import RunnableLambda


async def reverse(s: str) -> str:
    return s[::-1]


chain = RunnableLambda(func=reverse)

events = [event async for event in chain.astream_events("hello", version="v2")]

# Will produce the following events
# (run_id, and parent_ids has been omitted for brevity):
[
    {
        "data": {"input": "hello"},
        "event": "on_chain_start",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
    {
        "data": {"chunk": "olleh"},
        "event": "on_chain_stream",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
    {
        "data": {"output": "olleh"},
        "event": "on_chain_end",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
]

Example: Dispatch Custom Event

from langchain_core.callbacks.manager import (
    adispatch_custom_event,
)
from langchain_core.runnables import RunnableLambda, RunnableConfig
import asyncio


async def slow_thing(some_input: str, config: RunnableConfig) -> str:
    """Do something that takes a long time."""
    await asyncio.sleep(1) # Placeholder for some slow operation
    await adispatch_custom_event(
        "progress_event",
        {"message": "Finished step 1 of 3"},
        config=config # Must be included for python < 3.10
    )
    await asyncio.sleep(1) # Placeholder for some slow operation
    await adispatch_custom_event(
        "progress_event",
        {"message": "Finished step 2 of 3"},
        config=config # Must be included for python < 3.10
    )
    await asyncio.sleep(1) # Placeholder for some slow operation
    return "Done"

slow_thing = RunnableLambda(slow_thing)

async for event in slow_thing.astream_events("some_input", version="v2"):
    print(event)

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Any
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
version	The version of the schema to use either 'v2' or 'v1'. Users should use 'v2'. 'v1' is for backwards compatibility and will be deprecated in 0.4.0. No default will be assigned until the API is stabilized. custom events will only be surfaced in 'v2'. TYPE: Literal['v1', 'v2'] DEFAULT: 'v2'
include_names	Only include events from Runnable objects with matching names. TYPE: Sequence[str] | None DEFAULT: None
include_types	Only include events from Runnable objects with matching types. TYPE: Sequence[str] | None DEFAULT: None
include_tags	Only include events from Runnable objects with matching tags. TYPE: Sequence[str] | None DEFAULT: None
exclude_names	Exclude events from Runnable objects with matching names. TYPE: Sequence[str] | None DEFAULT: None
exclude_types	Exclude events from Runnable objects with matching types. TYPE: Sequence[str] | None DEFAULT: None
exclude_tags	Exclude events from Runnable objects with matching tags. TYPE: Sequence[str] | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. These will be passed to astream_log as this implementation of astream_events is built on top of astream_log. TYPE: Any DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[StreamEvent]	An async stream of StreamEvent.

RAISES	DESCRIPTION
NotImplementedError	If the version is not 'v1' or 'v2'.

transform

transform(
    input: Iterator[Input], config: RunnableConfig | None = None, **kwargs: Any | None
) -> Iterator[Output]

Transform inputs to outputs.

Default implementation of transform, which buffers input and calls astream.

Subclasses must override this method if they can start producing output while input is still being generated.

PARAMETER	DESCRIPTION
input	An iterator of inputs to the Runnable. TYPE: Iterator[Input]
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
Output	The output of the Runnable.

atransform async

atransform(
    input: AsyncIterator[Input],
    config: RunnableConfig | None = None,
    **kwargs: Any | None,
) -> AsyncIterator[Output]

Transform inputs to outputs.

Default implementation of atransform, which buffers input and calls astream.

Subclasses must override this method if they can start producing output while input is still being generated.

PARAMETER	DESCRIPTION
input	An async iterator of inputs to the Runnable. TYPE: AsyncIterator[Input]
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[Output]	The output of the Runnable.

bind

bind(**kwargs: Any) -> Runnable[Input, Output]

Bind arguments to a Runnable, returning a new Runnable.

Useful when a Runnable in a chain requires an argument that is not in the output of the previous Runnable or included in the user input.

PARAMETER	DESCRIPTION
**kwargs	The arguments to bind to the Runnable. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the arguments bound.

Example

from langchain_ollama import ChatOllama
from langchain_core.output_parsers import StrOutputParser

model = ChatOllama(model="llama3.1")

# Without bind
chain = model | StrOutputParser()

chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two three four five.'

# With bind
chain = model.bind(stop=["three"]) | StrOutputParser()

chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two'

with_config

with_config(
    config: RunnableConfig | None = None, **kwargs: Any
) -> Runnable[Input, Output]

Bind config to a Runnable, returning a new Runnable.

PARAMETER	DESCRIPTION
config	The config to bind to the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the config bound.

with_listeners

with_listeners(
    *,
    on_start: Callable[[Run], None]
    | Callable[[Run, RunnableConfig], None]
    | None = None,
    on_end: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None = None,
    on_error: Callable[[Run], None]
    | Callable[[Run, RunnableConfig], None]
    | None = None,
) -> Runnable[Input, Output]

Bind lifecycle listeners to a Runnable, returning a new Runnable.

The Run object contains information about the run, including its id, type, input, output, error, start_time, end_time, and any tags or metadata added to the run.

PARAMETER	DESCRIPTION
on_start	Called before the Runnable starts running, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None
on_end	Called after the Runnable finishes running, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None
on_error	Called if the Runnable throws an error, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the listeners bound.

Example

from langchain_core.runnables import RunnableLambda
from langchain_core.tracers.schemas import Run

import time


def test_runnable(time_to_sleep: int):
    time.sleep(time_to_sleep)


def fn_start(run_obj: Run):
    print("start_time:", run_obj.start_time)


def fn_end(run_obj: Run):
    print("end_time:", run_obj.end_time)


chain = RunnableLambda(test_runnable).with_listeners(
    on_start=fn_start, on_end=fn_end
)
chain.invoke(2)

with_alisteners

with_alisteners(
    *,
    on_start: AsyncListener | None = None,
    on_end: AsyncListener | None = None,
    on_error: AsyncListener | None = None,
) -> Runnable[Input, Output]

Bind async lifecycle listeners to a Runnable.

Returns a new Runnable.

The Run object contains information about the run, including its id, type, input, output, error, start_time, end_time, and any tags or metadata added to the run.

PARAMETER	DESCRIPTION
on_start	Called asynchronously before the Runnable starts running, with the Run object. TYPE: AsyncListener | None DEFAULT: None
on_end	Called asynchronously after the Runnable finishes running, with the Run object. TYPE: AsyncListener | None DEFAULT: None
on_error	Called asynchronously if the Runnable throws an error, with the Run object. TYPE: AsyncListener | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the listeners bound.

Example

from langchain_core.runnables import RunnableLambda, Runnable
from datetime import datetime, timezone
import time
import asyncio


def format_t(timestamp: float) -> str:
    return datetime.fromtimestamp(timestamp, tz=timezone.utc).isoformat()


async def test_runnable(time_to_sleep: int):
    print(f"Runnable[{time_to_sleep}s]: starts at {format_t(time.time())}")
    await asyncio.sleep(time_to_sleep)
    print(f"Runnable[{time_to_sleep}s]: ends at {format_t(time.time())}")


async def fn_start(run_obj: Runnable):
    print(f"on start callback starts at {format_t(time.time())}")
    await asyncio.sleep(3)
    print(f"on start callback ends at {format_t(time.time())}")


async def fn_end(run_obj: Runnable):
    print(f"on end callback starts at {format_t(time.time())}")
    await asyncio.sleep(2)
    print(f"on end callback ends at {format_t(time.time())}")


runnable = RunnableLambda(test_runnable).with_alisteners(
    on_start=fn_start, on_end=fn_end
)


async def concurrent_runs():
    await asyncio.gather(runnable.ainvoke(2), runnable.ainvoke(3))


asyncio.run(concurrent_runs())
# Result:
# on start callback starts at 2025-03-01T07:05:22.875378+00:00
# on start callback starts at 2025-03-01T07:05:22.875495+00:00
# on start callback ends at 2025-03-01T07:05:25.878862+00:00
# on start callback ends at 2025-03-01T07:05:25.878947+00:00
# Runnable[2s]: starts at 2025-03-01T07:05:25.879392+00:00
# Runnable[3s]: starts at 2025-03-01T07:05:25.879804+00:00
# Runnable[2s]: ends at 2025-03-01T07:05:27.881998+00:00
# on end callback starts at 2025-03-01T07:05:27.882360+00:00
# Runnable[3s]: ends at 2025-03-01T07:05:28.881737+00:00
# on end callback starts at 2025-03-01T07:05:28.882428+00:00
# on end callback ends at 2025-03-01T07:05:29.883893+00:00
# on end callback ends at 2025-03-01T07:05:30.884831+00:00

with_types

with_types(
    *, input_type: type[Input] | None = None, output_type: type[Output] | None = None
) -> Runnable[Input, Output]

Bind input and output types to a Runnable, returning a new Runnable.

PARAMETER	DESCRIPTION
input_type	The input type to bind to the Runnable. TYPE: type[Input] | None DEFAULT: None
output_type	The output type to bind to the Runnable. TYPE: type[Output] | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the types bound.

with_retry

with_retry(
    *,
    retry_if_exception_type: tuple[type[BaseException], ...] = (Exception,),
    wait_exponential_jitter: bool = True,
    exponential_jitter_params: ExponentialJitterParams | None = None,
    stop_after_attempt: int = 3,
) -> Runnable[Input, Output]

Create a new Runnable that retries the original Runnable on exceptions.

PARAMETER	DESCRIPTION
retry_if_exception_type	A tuple of exception types to retry on. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
wait_exponential_jitter	Whether to add jitter to the wait time between retries. TYPE: bool DEFAULT: True
stop_after_attempt	The maximum number of attempts to make before giving up. TYPE: int DEFAULT: 3
exponential_jitter_params	Parameters for tenacity.wait_exponential_jitter. Namely: initial, max, exp_base, and jitter (all float values). TYPE: ExponentialJitterParams | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable that retries the original Runnable on exceptions.

Example

from langchain_core.runnables import RunnableLambda

count = 0


def _lambda(x: int) -> None:
    global count
    count = count + 1
    if x == 1:
        raise ValueError("x is 1")
    else:
        pass


runnable = RunnableLambda(_lambda)
try:
    runnable.with_retry(
        stop_after_attempt=2,
        retry_if_exception_type=(ValueError,),
    ).invoke(1)
except ValueError:
    pass

assert count == 2

map

map() -> Runnable[list[Input], list[Output]]

Return a new Runnable that maps a list of inputs to a list of outputs.

Calls invoke with each input.

RETURNS	DESCRIPTION
Runnable[list[Input], list[Output]]	A new Runnable that maps a list of inputs to a list of outputs.

Example

from langchain_core.runnables import RunnableLambda


def _lambda(x: int) -> int:
    return x + 1


runnable = RunnableLambda(_lambda)
print(runnable.map().invoke([1, 2, 3]))  # [2, 3, 4]

with_fallbacks

with_fallbacks(
    fallbacks: Sequence[Runnable[Input, Output]],
    *,
    exceptions_to_handle: tuple[type[BaseException], ...] = (Exception,),
    exception_key: str | None = None,
) -> RunnableWithFallbacks[Input, Output]

Add fallbacks to a Runnable, returning a new Runnable.

The new Runnable will try the original Runnable, and then each fallback in order, upon failures.

PARAMETER	DESCRIPTION
fallbacks	A sequence of runnables to try if the original Runnable fails. TYPE: Sequence[Runnable[Input, Output]]
exceptions_to_handle	A tuple of exception types to handle. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
exception_key	If string is specified then handled exceptions will be passed to fallbacks as part of the input under the specified key. If None, exceptions will not be passed to fallbacks. If used, the base Runnable and its fallbacks must accept a dictionary as input. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableWithFallbacks[Input, Output]	A new Runnable that will try the original Runnable, and then each Fallback in order, upon failures.

Example

from typing import Iterator

from langchain_core.runnables import RunnableGenerator


def _generate_immediate_error(input: Iterator) -> Iterator[str]:
    raise ValueError()
    yield ""


def _generate(input: Iterator) -> Iterator[str]:
    yield from "foo bar"


runnable = RunnableGenerator(_generate_immediate_error).with_fallbacks(
    [RunnableGenerator(_generate)]
)
print("".join(runnable.stream({})))  # foo bar

PARAMETER	DESCRIPTION
fallbacks	A sequence of runnables to try if the original Runnable fails. TYPE: Sequence[Runnable[Input, Output]]
exceptions_to_handle	A tuple of exception types to handle. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
exception_key	If string is specified then handled exceptions will be passed to fallbacks as part of the input under the specified key. If None, exceptions will not be passed to fallbacks. If used, the base Runnable and its fallbacks must accept a dictionary as input. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableWithFallbacks[Input, Output]	A new Runnable that will try the original Runnable, and then each Fallback in order, upon failures.

as_tool

as_tool(
    args_schema: type[BaseModel] | None = None,
    *,
    name: str | None = None,
    description: str | None = None,
    arg_types: dict[str, type] | None = None,
) -> BaseTool

Create a BaseTool from a Runnable.

as_tool will instantiate a BaseTool with a name, description, and args_schema from a Runnable. Where possible, schemas are inferred from runnable.get_input_schema.

Alternatively (e.g., if the Runnable takes a dict as input and the specific dict keys are not typed), the schema can be specified directly with args_schema.

You can also pass arg_types to just specify the required arguments and their types.

PARAMETER	DESCRIPTION
args_schema	The schema for the tool. TYPE: type[BaseModel] | None DEFAULT: None
name	The name of the tool. TYPE: str | None DEFAULT: None
description	The description of the tool. TYPE: str | None DEFAULT: None
arg_types	A dictionary of argument names to types. TYPE: dict[str, type] | None DEFAULT: None

RETURNS	DESCRIPTION
BaseTool	A BaseTool instance.

Typed dict input:

from typing_extensions import TypedDict
from langchain_core.runnables import RunnableLambda


class Args(TypedDict):
    a: int
    b: list[int]


def f(x: Args) -> str:
    return str(x["a"] * max(x["b"]))


runnable = RunnableLambda(f)
as_tool = runnable.as_tool()
as_tool.invoke({"a": 3, "b": [1, 2]})

dict input, specifying schema via args_schema:

from typing import Any
from pydantic import BaseModel, Field
from langchain_core.runnables import RunnableLambda

def f(x: dict[str, Any]) -> str:
    return str(x["a"] * max(x["b"]))

class FSchema(BaseModel):
    """Apply a function to an integer and list of integers."""

    a: int = Field(..., description="Integer")
    b: list[int] = Field(..., description="List of ints")

runnable = RunnableLambda(f)
as_tool = runnable.as_tool(FSchema)
as_tool.invoke({"a": 3, "b": [1, 2]})

dict input, specifying schema via arg_types:

from typing import Any
from langchain_core.runnables import RunnableLambda


def f(x: dict[str, Any]) -> str:
    return str(x["a"] * max(x["b"]))


runnable = RunnableLambda(f)
as_tool = runnable.as_tool(arg_types={"a": int, "b": list[int]})
as_tool.invoke({"a": 3, "b": [1, 2]})

str input:

from langchain_core.runnables import RunnableLambda


def f(x: str) -> str:
    return x + "a"


def g(x: str) -> str:
    return x + "z"


runnable = RunnableLambda(f) | g
as_tool = runnable.as_tool()
as_tool.invoke("b")

__init__

__init__(*args: Any, **kwargs: Any) -> None

is_lc_serializable classmethod

is_lc_serializable() -> bool

Is this class serializable?

By design, even if a class inherits from Serializable, it is not serializable by default. This is to prevent accidental serialization of objects that should not be serialized.

RETURNS	DESCRIPTION
bool	Whether the class is serializable. Default is False.

get_lc_namespace classmethod

get_lc_namespace() -> list[str]

Get the namespace of the LangChain object.

For example, if the class is langchain.llms.openai.OpenAI, then the namespace is ["langchain", "llms", "openai"]

RETURNS	DESCRIPTION
list[str]	The namespace.

lc_id classmethod

lc_id() -> list[str]

Return a unique identifier for this class for serialization purposes.

The unique identifier is a list of strings that describes the path to the object.

For example, for the class langchain.llms.openai.OpenAI, the id is ["langchain", "llms", "openai", "OpenAI"].

to_json

to_json() -> SerializedConstructor | SerializedNotImplemented

Serialize the Runnable to JSON.

RETURNS	DESCRIPTION
SerializedConstructor | SerializedNotImplemented	A JSON-serializable representation of the Runnable.

to_json_not_implemented

to_json_not_implemented() -> SerializedNotImplemented

Serialize a "not implemented" object.

RETURNS	DESCRIPTION
SerializedNotImplemented	SerializedNotImplemented.

configurable_fields

configurable_fields(
    **kwargs: AnyConfigurableField,
) -> RunnableSerializable[Input, Output]

Configure particular Runnable fields at runtime.

PARAMETER	DESCRIPTION
**kwargs	A dictionary of ConfigurableField instances to configure. TYPE: AnyConfigurableField DEFAULT: {}

RAISES	DESCRIPTION
ValueError	If a configuration key is not found in the Runnable.

RETURNS	DESCRIPTION
RunnableSerializable[Input, Output]	A new Runnable with the fields configured.

from langchain_core.runnables import ConfigurableField
from langchain_openai import ChatOpenAI

model = ChatOpenAI(max_tokens=20).configurable_fields(
    max_tokens=ConfigurableField(
        id="output_token_number",
        name="Max tokens in the output",
        description="The maximum number of tokens in the output",
    )
)

# max_tokens = 20
print("max_tokens_20: ", model.invoke("tell me something about chess").content)

# max_tokens = 200
print(
    "max_tokens_200: ",
    model.with_config(configurable={"output_token_number": 200})
    .invoke("tell me something about chess")
    .content,
)

configurable_alternatives

configurable_alternatives(
    which: ConfigurableField,
    *,
    default_key: str = "default",
    prefix_keys: bool = False,
    **kwargs: Runnable[Input, Output] | Callable[[], Runnable[Input, Output]],
) -> RunnableSerializable[Input, Output]

Configure alternatives for Runnable objects that can be set at runtime.

PARAMETER	DESCRIPTION
which	The ConfigurableField instance that will be used to select the alternative. TYPE: ConfigurableField
default_key	The default key to use if no alternative is selected. TYPE: str DEFAULT: 'default'
prefix_keys	Whether to prefix the keys with the ConfigurableField id. TYPE: bool DEFAULT: False
**kwargs	A dictionary of keys to Runnable instances or callables that return Runnable instances. TYPE: Runnable[Input, Output] | Callable[[], Runnable[Input, Output]] DEFAULT: {}

RETURNS	DESCRIPTION
RunnableSerializable[Input, Output]	A new Runnable with the alternatives configured.

from langchain_anthropic import ChatAnthropic
from langchain_core.runnables.utils import ConfigurableField
from langchain_openai import ChatOpenAI

model = ChatAnthropic(
    model_name="claude-sonnet-4-5-20250929"
).configurable_alternatives(
    ConfigurableField(id="llm"),
    default_key="anthropic",
    openai=ChatOpenAI(),
)

# uses the default model ChatAnthropic
print(model.invoke("which organization created you?").content)

# uses ChatOpenAI
print(
    model.with_config(configurable={"llm": "openai"})
    .invoke("which organization created you?")
    .content
)

validate_environment classmethod

validate_environment(values: dict) -> Any

Validate the environment.

ExaFindSimilarResults

Bases: BaseTool

Tool that queries the Metaphor Search API and gets back json.

METHOD	DESCRIPTION
get_name	Get the name of the Runnable.
get_input_schema	The tool's input schema.
get_input_jsonschema	Get a JSON schema that represents the input to the Runnable.
get_output_schema	Get a Pydantic model that can be used to validate output to the Runnable.
get_output_jsonschema	Get a JSON schema that represents the output of the Runnable.
config_schema	The type of config this Runnable accepts specified as a Pydantic model.
get_config_jsonschema	Get a JSON schema that represents the config of the Runnable.
get_graph	Return a graph representation of this Runnable.
get_prompts	Return a list of prompts used by this Runnable.
__or__	Runnable "or" operator.
__ror__	Runnable "reverse-or" operator.
pipe	Pipe Runnable objects.
pick	Pick keys from the output dict of this Runnable.
assign	Assigns new fields to the dict output of this Runnable.
invoke	Transform a single input into an output.
ainvoke	Transform a single input into an output.
batch	Default implementation runs invoke in parallel using a thread pool executor.
batch_as_completed	Run invoke in parallel on a list of inputs.
abatch	Default implementation runs ainvoke in parallel using asyncio.gather.
abatch_as_completed	Run ainvoke in parallel on a list of inputs.
stream	Default implementation of stream, which calls invoke.
astream	Default implementation of astream, which calls ainvoke.
astream_log	Stream all output from a Runnable, as reported to the callback system.
astream_events	Generate a stream of events.
transform	Transform inputs to outputs.
atransform	Transform inputs to outputs.
bind	Bind arguments to a Runnable, returning a new Runnable.
with_config	Bind config to a Runnable, returning a new Runnable.
with_listeners	Bind lifecycle listeners to a Runnable, returning a new Runnable.
with_alisteners	Bind async lifecycle listeners to a Runnable.
with_types	Bind input and output types to a Runnable, returning a new Runnable.
with_retry	Create a new Runnable that retries the original Runnable on exceptions.
map	Return a new Runnable that maps a list of inputs to a list of outputs.
with_fallbacks	Add fallbacks to a Runnable, returning a new Runnable.
as_tool	Create a BaseTool from a Runnable.
__init__	Initialize the tool.
is_lc_serializable	Is this class serializable?
get_lc_namespace	Get the namespace of the LangChain object.
lc_id	Return a unique identifier for this class for serialization purposes.
to_json	Serialize the Runnable to JSON.
to_json_not_implemented	Serialize a "not implemented" object.
configurable_fields	Configure particular Runnable fields at runtime.
configurable_alternatives	Configure alternatives for Runnable objects that can be set at runtime.
__init_subclass__	Validate the tool class definition during subclass creation.
run	Run the tool.
arun	Run the tool asynchronously.
validate_environment	Validate the environment.

InputType property

InputType: type[Input]

Input type.

The type of input this Runnable accepts specified as a type annotation.

RAISES	DESCRIPTION
TypeError	If the input type cannot be inferred.

OutputType property

OutputType: type[Output]

Output Type.

The type of output this Runnable produces specified as a type annotation.

RAISES	DESCRIPTION
TypeError	If the output type cannot be inferred.

input_schema property

input_schema: type[BaseModel]

The type of input this Runnable accepts specified as a Pydantic model.

output_schema property

output_schema: type[BaseModel]

Output schema.

The type of output this Runnable produces specified as a Pydantic model.

config_specs property

config_specs: list[ConfigurableFieldSpec]

List configurable fields for this Runnable.

lc_secrets property

lc_secrets: dict[str, str]

A map of constructor argument names to secret ids.

For example, {"openai_api_key": "OPENAI_API_KEY"}

lc_attributes property

lc_attributes: dict

List of attribute names that should be included in the serialized kwargs.

These attributes must be accepted by the constructor.

Default is an empty dictionary.

args_schema class-attribute instance-attribute

args_schema: Annotated[ArgsSchema | None, SkipValidation()] = Field(
    default=None, description="The tool schema."
)

Pydantic model class to validate and parse the tool's input arguments.

Args schema should be either:

• A subclass of pydantic.BaseModel.
• A subclass of pydantic.v1.BaseModel if accessing v1 namespace in pydantic 2
• A JSON schema dict

return_direct class-attribute instance-attribute

return_direct: bool = False

Whether to return the tool's output directly.

Setting this to True means that after the tool is called, the AgentExecutor will stop looping.

verbose class-attribute instance-attribute

verbose: bool = False

Whether to log the tool's progress.

callbacks class-attribute instance-attribute

callbacks: Callbacks = Field(default=None, exclude=True)

Callbacks to be called during tool execution.

tags class-attribute instance-attribute

tags: list[str] | None = None

Optional list of tags associated with the tool.

These tags will be associated with each call to this tool, and passed as arguments to the handlers defined in callbacks.

You can use these to, e.g., identify a specific instance of a tool with its use case.

metadata class-attribute instance-attribute

metadata: dict[str, Any] | None = None

Optional metadata associated with the tool.

This metadata will be associated with each call to this tool, and passed as arguments to the handlers defined in callbacks.

You can use these to, e.g., identify a specific instance of a tool with its use case.

handle_tool_error class-attribute instance-attribute

handle_tool_error: bool | str | Callable[[ToolException], str] | None = False

Handle the content of the ToolException thrown.

handle_validation_error class-attribute instance-attribute

handle_validation_error: (
    bool | str | Callable[[ValidationError | ValidationError], str] | None
) = False

Handle the content of the ValidationError thrown.

response_format class-attribute instance-attribute

response_format: Literal['content', 'content_and_artifact'] = 'content'

The tool response format.

If 'content' then the output of the tool is interpreted as the contents of a ToolMessage. If 'content_and_artifact' then the output is expected to be a two-tuple corresponding to the (content, artifact) of a ToolMessage.

is_single_input property

is_single_input: bool

Check if the tool accepts only a single input argument.

RETURNS	DESCRIPTION
bool	True if the tool has only one input argument, False otherwise.

args property

args: dict

Get the tool's input arguments schema.

RETURNS	DESCRIPTION
dict	dict containing the tool's argument properties.

tool_call_schema property

tool_call_schema: ArgsSchema

Get the schema for tool calls, excluding injected arguments.

RETURNS	DESCRIPTION
ArgsSchema	The schema that should be used for tool calls from language models.

name class-attribute instance-attribute

name: str = 'exa_find_similar_results_json'

The unique name of the tool that clearly communicates its purpose.

description class-attribute instance-attribute

description: str = "A wrapper around Exa Find Similar. Input should be an Exa-optimized query. Output is a JSON array of the query results"

Used to tell the model how/when/why to use the tool.

You can provide few-shot examples as a part of the description.

get_name

get_name(suffix: str | None = None, *, name: str | None = None) -> str

Get the name of the Runnable.

PARAMETER	DESCRIPTION
suffix	An optional suffix to append to the name. TYPE: str | None DEFAULT: None
name	An optional name to use instead of the Runnable's name. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
str	The name of the Runnable.

get_input_schema

get_input_schema(config: RunnableConfig | None = None) -> type[BaseModel]

The tool's input schema.

PARAMETER	DESCRIPTION
config	The configuration for the tool. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	The input schema for the tool.

get_input_jsonschema

get_input_jsonschema(config: RunnableConfig | None = None) -> dict[str, Any]

Get a JSON schema that represents the input to the Runnable.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the input to the Runnable.

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


runnable = RunnableLambda(add_one)

print(runnable.get_input_jsonschema())

Added in langchain-core 0.3.0

get_output_schema

get_output_schema(config: RunnableConfig | None = None) -> type[BaseModel]

Get a Pydantic model that can be used to validate output to the Runnable.

Runnable objects that leverage the configurable_fields and configurable_alternatives methods will have a dynamic output schema that depends on which configuration the Runnable is invoked with.

This method allows to get an output schema for a specific configuration.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	A Pydantic model that can be used to validate output.

get_output_jsonschema

get_output_jsonschema(config: RunnableConfig | None = None) -> dict[str, Any]

Get a JSON schema that represents the output of the Runnable.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the output of the Runnable.

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


runnable = RunnableLambda(add_one)

print(runnable.get_output_jsonschema())

Added in langchain-core 0.3.0

config_schema

config_schema(*, include: Sequence[str] | None = None) -> type[BaseModel]

The type of config this Runnable accepts specified as a Pydantic model.

To mark a field as configurable, see the configurable_fields and configurable_alternatives methods.

PARAMETER	DESCRIPTION
include	A list of fields to include in the config schema. TYPE: Sequence[str] | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	A Pydantic model that can be used to validate config.

get_config_jsonschema

get_config_jsonschema(*, include: Sequence[str] | None = None) -> dict[str, Any]

Get a JSON schema that represents the config of the Runnable.

PARAMETER	DESCRIPTION
include	A list of fields to include in the config schema. TYPE: Sequence[str] | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the config of the Runnable.

Added in langchain-core 0.3.0

get_graph

get_graph(config: RunnableConfig | None = None) -> Graph

Return a graph representation of this Runnable.

get_prompts

get_prompts(config: RunnableConfig | None = None) -> list[BasePromptTemplate]

Return a list of prompts used by this Runnable.

__or__

__or__(
    other: Runnable[Any, Other]
    | Callable[[Iterator[Any]], Iterator[Other]]
    | Callable[[AsyncIterator[Any]], AsyncIterator[Other]]
    | Callable[[Any], Other]
    | Mapping[str, Runnable[Any, Other] | Callable[[Any], Other] | Any],
) -> RunnableSerializable[Input, Other]

Runnable "or" operator.

Compose this Runnable with another object to create a RunnableSequence.

PARAMETER	DESCRIPTION
other	Another Runnable or a Runnable-like object. TYPE: Runnable[Any, Other] | Callable[[Iterator[Any]], Iterator[Other]] | Callable[[AsyncIterator[Any]], AsyncIterator[Other]] | Callable[[Any], Other] | Mapping[str, Runnable[Any, Other] | Callable[[Any], Other] | Any]

RETURNS	DESCRIPTION
RunnableSerializable[Input, Other]	A new Runnable.

__ror__

__ror__(
    other: Runnable[Other, Any]
    | Callable[[Iterator[Other]], Iterator[Any]]
    | Callable[[AsyncIterator[Other]], AsyncIterator[Any]]
    | Callable[[Other], Any]
    | Mapping[str, Runnable[Other, Any] | Callable[[Other], Any] | Any],
) -> RunnableSerializable[Other, Output]

Runnable "reverse-or" operator.

Compose this Runnable with another object to create a RunnableSequence.

PARAMETER	DESCRIPTION
other	Another Runnable or a Runnable-like object. TYPE: Runnable[Other, Any] | Callable[[Iterator[Other]], Iterator[Any]] | Callable[[AsyncIterator[Other]], AsyncIterator[Any]] | Callable[[Other], Any] | Mapping[str, Runnable[Other, Any] | Callable[[Other], Any] | Any]

RETURNS	DESCRIPTION
RunnableSerializable[Other, Output]	A new Runnable.

pipe

pipe(
    *others: Runnable[Any, Other] | Callable[[Any], Other], name: str | None = None
) -> RunnableSerializable[Input, Other]

Pipe Runnable objects.

Compose this Runnable with Runnable-like objects to make a RunnableSequence.

Equivalent to RunnableSequence(self, *others) or self | others[0] | ...

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


def mul_two(x: int) -> int:
    return x * 2


runnable_1 = RunnableLambda(add_one)
runnable_2 = RunnableLambda(mul_two)
sequence = runnable_1.pipe(runnable_2)
# Or equivalently:
# sequence = runnable_1 | runnable_2
# sequence = RunnableSequence(first=runnable_1, last=runnable_2)
sequence.invoke(1)
await sequence.ainvoke(1)
# -> 4

sequence.batch([1, 2, 3])
await sequence.abatch([1, 2, 3])
# -> [4, 6, 8]

PARAMETER	DESCRIPTION
*others	Other Runnable or Runnable-like objects to compose TYPE: Runnable[Any, Other] | Callable[[Any], Other] DEFAULT: ()
name	An optional name for the resulting RunnableSequence. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableSerializable[Input, Other]	A new Runnable.

pick

pick(keys: str | list[str]) -> RunnableSerializable[Any, Any]

Pick keys from the output dict of this Runnable.

Pick a single key:

import json

from langchain_core.runnables import RunnableLambda, RunnableMap

as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)
chain = RunnableMap(str=as_str, json=as_json)

chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3]}

json_only_chain = chain.pick("json")
json_only_chain.invoke("[1, 2, 3]")
# -> [1, 2, 3]

Pick a list of keys:

from typing import Any

import json

from langchain_core.runnables import RunnableLambda, RunnableMap

as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)


def as_bytes(x: Any) -> bytes:
    return bytes(x, "utf-8")


chain = RunnableMap(str=as_str, json=as_json, bytes=RunnableLambda(as_bytes))

chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3], "bytes": b"[1, 2, 3]"}

json_and_bytes_chain = chain.pick(["json", "bytes"])
json_and_bytes_chain.invoke("[1, 2, 3]")
# -> {"json": [1, 2, 3], "bytes": b"[1, 2, 3]"}

PARAMETER	DESCRIPTION
keys	A key or list of keys to pick from the output dict. TYPE: str | list[str]

RETURNS	DESCRIPTION
RunnableSerializable[Any, Any]	a new Runnable.

assign

assign(
    **kwargs: Runnable[dict[str, Any], Any]
    | Callable[[dict[str, Any]], Any]
    | Mapping[str, Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any]],
) -> RunnableSerializable[Any, Any]

Assigns new fields to the dict output of this Runnable.

from langchain_core.language_models.fake import FakeStreamingListLLM
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import SystemMessagePromptTemplate
from langchain_core.runnables import Runnable
from operator import itemgetter

prompt = (
    SystemMessagePromptTemplate.from_template("You are a nice assistant.")
    + "{question}"
)
model = FakeStreamingListLLM(responses=["foo-lish"])

chain: Runnable = prompt | model | {"str": StrOutputParser()}

chain_with_assign = chain.assign(hello=itemgetter("str") | model)

print(chain_with_assign.input_schema.model_json_schema())
# {'title': 'PromptInput', 'type': 'object', 'properties':
{'question': {'title': 'Question', 'type': 'string'}}}
print(chain_with_assign.output_schema.model_json_schema())
# {'title': 'RunnableSequenceOutput', 'type': 'object', 'properties':
{'str': {'title': 'Str',
'type': 'string'}, 'hello': {'title': 'Hello', 'type': 'string'}}}

PARAMETER	DESCRIPTION
**kwargs	A mapping of keys to Runnable or Runnable-like objects that will be invoked with the entire output dict of this Runnable. TYPE: Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any] | Mapping[str, Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any]] DEFAULT: {}

RETURNS	DESCRIPTION
RunnableSerializable[Any, Any]	A new Runnable.

invoke

invoke(
    input: str | dict | ToolCall, config: RunnableConfig | None = None, **kwargs: Any
) -> Any

Transform a single input into an output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
Output	The output of the Runnable.

ainvoke async

ainvoke(
    input: str | dict | ToolCall, config: RunnableConfig | None = None, **kwargs: Any
) -> Any

Transform a single input into an output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
Output	The output of the Runnable.

batch

batch(
    inputs: list[Input],
    config: RunnableConfig | list[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> list[Output]

Default implementation runs invoke in parallel using a thread pool executor.

The default implementation of batch works well for IO bound runnables.

Subclasses must override this method if they can batch more efficiently; e.g., if the underlying Runnable uses an API which supports a batch mode.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: list[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | list[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

RETURNS	DESCRIPTION
list[Output]	A list of outputs from the Runnable.

batch_as_completed

batch_as_completed(
    inputs: Sequence[Input],
    config: RunnableConfig | Sequence[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> Iterator[tuple[int, Output | Exception]]

Run invoke in parallel on a list of inputs.

Yields results as they complete.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: Sequence[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | Sequence[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
tuple[int, Output | Exception]	Tuples of the index of the input and the output from the Runnable.

abatch async

abatch(
    inputs: list[Input],
    config: RunnableConfig | list[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> list[Output]

Default implementation runs ainvoke in parallel using asyncio.gather.

The default implementation of batch works well for IO bound runnables.

Subclasses must override this method if they can batch more efficiently; e.g., if the underlying Runnable uses an API which supports a batch mode.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: list[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | list[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

RETURNS	DESCRIPTION
list[Output]	A list of outputs from the Runnable.

abatch_as_completed async

abatch_as_completed(
    inputs: Sequence[Input],
    config: RunnableConfig | Sequence[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> AsyncIterator[tuple[int, Output | Exception]]

Run ainvoke in parallel on a list of inputs.

Yields results as they complete.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: Sequence[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | Sequence[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[tuple[int, Output | Exception]]	A tuple of the index of the input and the output from the Runnable.

stream

stream(
    input: Input, config: RunnableConfig | None = None, **kwargs: Any | None
) -> Iterator[Output]

Default implementation of stream, which calls invoke.

Subclasses must override this method if they support streaming output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
Output	The output of the Runnable.

astream async

astream(
    input: Input, config: RunnableConfig | None = None, **kwargs: Any | None
) -> AsyncIterator[Output]

Default implementation of astream, which calls ainvoke.

Subclasses must override this method if they support streaming output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[Output]	The output of the Runnable.

astream_log async

astream_log(
    input: Any,
    config: RunnableConfig | None = None,
    *,
    diff: bool = True,
    with_streamed_output_list: bool = True,
    include_names: Sequence[str] | None = None,
    include_types: Sequence[str] | None = None,
    include_tags: Sequence[str] | None = None,
    exclude_names: Sequence[str] | None = None,
    exclude_types: Sequence[str] | None = None,
    exclude_tags: Sequence[str] | None = None,
    **kwargs: Any,
) -> AsyncIterator[RunLogPatch] | AsyncIterator[RunLog]

Stream all output from a Runnable, as reported to the callback system.

This includes all inner runs of LLMs, Retrievers, Tools, etc.

Output is streamed as Log objects, which include a list of Jsonpatch ops that describe how the state of the run has changed in each step, and the final state of the run.

The Jsonpatch ops can be applied in order to construct state.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Any
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
diff	Whether to yield diffs between each step or the current state. TYPE: bool DEFAULT: True
with_streamed_output_list	Whether to yield the streamed_output list. TYPE: bool DEFAULT: True
include_names	Only include logs with these names. TYPE: Sequence[str] | None DEFAULT: None
include_types	Only include logs with these types. TYPE: Sequence[str] | None DEFAULT: None
include_tags	Only include logs with these tags. TYPE: Sequence[str] | None DEFAULT: None
exclude_names	Exclude logs with these names. TYPE: Sequence[str] | None DEFAULT: None
exclude_types	Exclude logs with these types. TYPE: Sequence[str] | None DEFAULT: None
exclude_tags	Exclude logs with these tags. TYPE: Sequence[str] | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[RunLogPatch] | AsyncIterator[RunLog]	A RunLogPatch or RunLog object.

astream_events async

astream_events(
    input: Any,
    config: RunnableConfig | None = None,
    *,
    version: Literal["v1", "v2"] = "v2",
    include_names: Sequence[str] | None = None,
    include_types: Sequence[str] | None = None,
    include_tags: Sequence[str] | None = None,
    exclude_names: Sequence[str] | None = None,
    exclude_types: Sequence[str] | None = None,
    exclude_tags: Sequence[str] | None = None,
    **kwargs: Any,
) -> AsyncIterator[StreamEvent]

Generate a stream of events.

Use to create an iterator over StreamEvent that provide real-time information about the progress of the Runnable, including StreamEvent from intermediate results.

A StreamEvent is a dictionary with the following schema:

• event: Event names are of the format: on_[runnable_type]_(start|stream|end).
• name: The name of the Runnable that generated the event.
• run_id: Randomly generated ID associated with the given execution of the Runnable that emitted the event. A child Runnable that gets invoked as part of the execution of a parent Runnable is assigned its own unique ID.
• parent_ids: The IDs of the parent runnables that generated the event. The root Runnable will have an empty list. The order of the parent IDs is from the root to the immediate parent. Only available for v2 version of the API. The v1 version of the API will return an empty list.
• tags: The tags of the Runnable that generated the event.
• metadata: The metadata of the Runnable that generated the event.
• data: The data associated with the event. The contents of this field depend on the type of event. See the table below for more details.

Below is a table that illustrates some events that might be emitted by various chains. Metadata fields have been omitted from the table for brevity. Chain definitions have been included after the table.

Note

This reference table is for the v2 version of the schema.

event	name	chunk	input	output
on_chat_model_start	'[model name]'		{"messages": [[SystemMessage, HumanMessage]]}
on_chat_model_stream	'[model name]'	AIMessageChunk(content="hello")
on_chat_model_end	'[model name]'		{"messages": [[SystemMessage, HumanMessage]]}	AIMessageChunk(content="hello world")
on_llm_start	'[model name]'		{'input': 'hello'}
on_llm_stream	'[model name]'	'Hello'
on_llm_end	'[model name]'		'Hello human!'
on_chain_start	'format_docs'
on_chain_stream	'format_docs'	'hello world!, goodbye world!'
on_chain_end	'format_docs'		[Document(...)]	'hello world!, goodbye world!'
on_tool_start	'some_tool'		{"x": 1, "y": "2"}
on_tool_end	'some_tool'			{"x": 1, "y": "2"}
on_retriever_start	'[retriever name]'		{"query": "hello"}
on_retriever_end	'[retriever name]'		{"query": "hello"}	[Document(...), ..]
on_prompt_start	'[template_name]'		{"question": "hello"}
on_prompt_end	'[template_name]'		{"question": "hello"}	ChatPromptValue(messages: [SystemMessage, ...])

In addition to the standard events, users can also dispatch custom events (see example below).

Custom events will be only be surfaced with in the v2 version of the API!

A custom event has following format:

Attribute	Type	Description
name	str	A user defined name for the event.
data	Any	The data associated with the event. This can be anything, though we suggest making it JSON serializable.

Here are declarations associated with the standard events shown above:

format_docs:

def format_docs(docs: list[Document]) -> str:
    '''Format the docs.'''
    return ", ".join([doc.page_content for doc in docs])


format_docs = RunnableLambda(format_docs)

some_tool:

@tool
def some_tool(x: int, y: str) -> dict:
    '''Some_tool.'''
    return {"x": x, "y": y}

prompt:

template = ChatPromptTemplate.from_messages(
    [
        ("system", "You are Cat Agent 007"),
        ("human", "{question}"),
    ]
).with_config({"run_name": "my_template", "tags": ["my_template"]})

For instance:

from langchain_core.runnables import RunnableLambda


async def reverse(s: str) -> str:
    return s[::-1]


chain = RunnableLambda(func=reverse)

events = [event async for event in chain.astream_events("hello", version="v2")]

# Will produce the following events
# (run_id, and parent_ids has been omitted for brevity):
[
    {
        "data": {"input": "hello"},
        "event": "on_chain_start",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
    {
        "data": {"chunk": "olleh"},
        "event": "on_chain_stream",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
    {
        "data": {"output": "olleh"},
        "event": "on_chain_end",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
]

Example: Dispatch Custom Event

from langchain_core.callbacks.manager import (
    adispatch_custom_event,
)
from langchain_core.runnables import RunnableLambda, RunnableConfig
import asyncio


async def slow_thing(some_input: str, config: RunnableConfig) -> str:
    """Do something that takes a long time."""
    await asyncio.sleep(1) # Placeholder for some slow operation
    await adispatch_custom_event(
        "progress_event",
        {"message": "Finished step 1 of 3"},
        config=config # Must be included for python < 3.10
    )
    await asyncio.sleep(1) # Placeholder for some slow operation
    await adispatch_custom_event(
        "progress_event",
        {"message": "Finished step 2 of 3"},
        config=config # Must be included for python < 3.10
    )
    await asyncio.sleep(1) # Placeholder for some slow operation
    return "Done"

slow_thing = RunnableLambda(slow_thing)

async for event in slow_thing.astream_events("some_input", version="v2"):
    print(event)

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Any
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
version	The version of the schema to use either 'v2' or 'v1'. Users should use 'v2'. 'v1' is for backwards compatibility and will be deprecated in 0.4.0. No default will be assigned until the API is stabilized. custom events will only be surfaced in 'v2'. TYPE: Literal['v1', 'v2'] DEFAULT: 'v2'
include_names	Only include events from Runnable objects with matching names. TYPE: Sequence[str] | None DEFAULT: None
include_types	Only include events from Runnable objects with matching types. TYPE: Sequence[str] | None DEFAULT: None
include_tags	Only include events from Runnable objects with matching tags. TYPE: Sequence[str] | None DEFAULT: None
exclude_names	Exclude events from Runnable objects with matching names. TYPE: Sequence[str] | None DEFAULT: None
exclude_types	Exclude events from Runnable objects with matching types. TYPE: Sequence[str] | None DEFAULT: None
exclude_tags	Exclude events from Runnable objects with matching tags. TYPE: Sequence[str] | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. These will be passed to astream_log as this implementation of astream_events is built on top of astream_log. TYPE: Any DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[StreamEvent]	An async stream of StreamEvent.

RAISES	DESCRIPTION
NotImplementedError	If the version is not 'v1' or 'v2'.

transform

transform(
    input: Iterator[Input], config: RunnableConfig | None = None, **kwargs: Any | None
) -> Iterator[Output]

Transform inputs to outputs.

Default implementation of transform, which buffers input and calls astream.

Subclasses must override this method if they can start producing output while input is still being generated.

PARAMETER	DESCRIPTION
input	An iterator of inputs to the Runnable. TYPE: Iterator[Input]
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
Output	The output of the Runnable.

atransform async

atransform(
    input: AsyncIterator[Input],
    config: RunnableConfig | None = None,
    **kwargs: Any | None,
) -> AsyncIterator[Output]

Transform inputs to outputs.

Default implementation of atransform, which buffers input and calls astream.

Subclasses must override this method if they can start producing output while input is still being generated.

PARAMETER	DESCRIPTION
input	An async iterator of inputs to the Runnable. TYPE: AsyncIterator[Input]
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[Output]	The output of the Runnable.

bind

bind(**kwargs: Any) -> Runnable[Input, Output]

Bind arguments to a Runnable, returning a new Runnable.

Useful when a Runnable in a chain requires an argument that is not in the output of the previous Runnable or included in the user input.

PARAMETER	DESCRIPTION
**kwargs	The arguments to bind to the Runnable. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the arguments bound.

Example

from langchain_ollama import ChatOllama
from langchain_core.output_parsers import StrOutputParser

model = ChatOllama(model="llama3.1")

# Without bind
chain = model | StrOutputParser()

chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two three four five.'

# With bind
chain = model.bind(stop=["three"]) | StrOutputParser()

chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two'

with_config

with_config(
    config: RunnableConfig | None = None, **kwargs: Any
) -> Runnable[Input, Output]

Bind config to a Runnable, returning a new Runnable.

PARAMETER	DESCRIPTION
config	The config to bind to the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the config bound.

with_listeners

with_listeners(
    *,
    on_start: Callable[[Run], None]
    | Callable[[Run, RunnableConfig], None]
    | None = None,
    on_end: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None = None,
    on_error: Callable[[Run], None]
    | Callable[[Run, RunnableConfig], None]
    | None = None,
) -> Runnable[Input, Output]

Bind lifecycle listeners to a Runnable, returning a new Runnable.

The Run object contains information about the run, including its id, type, input, output, error, start_time, end_time, and any tags or metadata added to the run.

PARAMETER	DESCRIPTION
on_start	Called before the Runnable starts running, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None
on_end	Called after the Runnable finishes running, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None
on_error	Called if the Runnable throws an error, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the listeners bound.

Example

from langchain_core.runnables import RunnableLambda
from langchain_core.tracers.schemas import Run

import time


def test_runnable(time_to_sleep: int):
    time.sleep(time_to_sleep)


def fn_start(run_obj: Run):
    print("start_time:", run_obj.start_time)


def fn_end(run_obj: Run):
    print("end_time:", run_obj.end_time)


chain = RunnableLambda(test_runnable).with_listeners(
    on_start=fn_start, on_end=fn_end
)
chain.invoke(2)

with_alisteners

with_alisteners(
    *,
    on_start: AsyncListener | None = None,
    on_end: AsyncListener | None = None,
    on_error: AsyncListener | None = None,
) -> Runnable[Input, Output]

Bind async lifecycle listeners to a Runnable.

Returns a new Runnable.

The Run object contains information about the run, including its id, type, input, output, error, start_time, end_time, and any tags or metadata added to the run.

PARAMETER	DESCRIPTION
on_start	Called asynchronously before the Runnable starts running, with the Run object. TYPE: AsyncListener | None DEFAULT: None
on_end	Called asynchronously after the Runnable finishes running, with the Run object. TYPE: AsyncListener | None DEFAULT: None
on_error	Called asynchronously if the Runnable throws an error, with the Run object. TYPE: AsyncListener | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the listeners bound.

Example

from langchain_core.runnables import RunnableLambda, Runnable
from datetime import datetime, timezone
import time
import asyncio


def format_t(timestamp: float) -> str:
    return datetime.fromtimestamp(timestamp, tz=timezone.utc).isoformat()


async def test_runnable(time_to_sleep: int):
    print(f"Runnable[{time_to_sleep}s]: starts at {format_t(time.time())}")
    await asyncio.sleep(time_to_sleep)
    print(f"Runnable[{time_to_sleep}s]: ends at {format_t(time.time())}")


async def fn_start(run_obj: Runnable):
    print(f"on start callback starts at {format_t(time.time())}")
    await asyncio.sleep(3)
    print(f"on start callback ends at {format_t(time.time())}")


async def fn_end(run_obj: Runnable):
    print(f"on end callback starts at {format_t(time.time())}")
    await asyncio.sleep(2)
    print(f"on end callback ends at {format_t(time.time())}")


runnable = RunnableLambda(test_runnable).with_alisteners(
    on_start=fn_start, on_end=fn_end
)


async def concurrent_runs():
    await asyncio.gather(runnable.ainvoke(2), runnable.ainvoke(3))


asyncio.run(concurrent_runs())
# Result:
# on start callback starts at 2025-03-01T07:05:22.875378+00:00
# on start callback starts at 2025-03-01T07:05:22.875495+00:00
# on start callback ends at 2025-03-01T07:05:25.878862+00:00
# on start callback ends at 2025-03-01T07:05:25.878947+00:00
# Runnable[2s]: starts at 2025-03-01T07:05:25.879392+00:00
# Runnable[3s]: starts at 2025-03-01T07:05:25.879804+00:00
# Runnable[2s]: ends at 2025-03-01T07:05:27.881998+00:00
# on end callback starts at 2025-03-01T07:05:27.882360+00:00
# Runnable[3s]: ends at 2025-03-01T07:05:28.881737+00:00
# on end callback starts at 2025-03-01T07:05:28.882428+00:00
# on end callback ends at 2025-03-01T07:05:29.883893+00:00
# on end callback ends at 2025-03-01T07:05:30.884831+00:00

with_types

with_types(
    *, input_type: type[Input] | None = None, output_type: type[Output] | None = None
) -> Runnable[Input, Output]

Bind input and output types to a Runnable, returning a new Runnable.

PARAMETER	DESCRIPTION
input_type	The input type to bind to the Runnable. TYPE: type[Input] | None DEFAULT: None
output_type	The output type to bind to the Runnable. TYPE: type[Output] | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the types bound.

with_retry

with_retry(
    *,
    retry_if_exception_type: tuple[type[BaseException], ...] = (Exception,),
    wait_exponential_jitter: bool = True,
    exponential_jitter_params: ExponentialJitterParams | None = None,
    stop_after_attempt: int = 3,
) -> Runnable[Input, Output]

Create a new Runnable that retries the original Runnable on exceptions.

PARAMETER	DESCRIPTION
retry_if_exception_type	A tuple of exception types to retry on. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
wait_exponential_jitter	Whether to add jitter to the wait time between retries. TYPE: bool DEFAULT: True
stop_after_attempt	The maximum number of attempts to make before giving up. TYPE: int DEFAULT: 3
exponential_jitter_params	Parameters for tenacity.wait_exponential_jitter. Namely: initial, max, exp_base, and jitter (all float values). TYPE: ExponentialJitterParams | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable that retries the original Runnable on exceptions.

Example

from langchain_core.runnables import RunnableLambda

count = 0


def _lambda(x: int) -> None:
    global count
    count = count + 1
    if x == 1:
        raise ValueError("x is 1")
    else:
        pass


runnable = RunnableLambda(_lambda)
try:
    runnable.with_retry(
        stop_after_attempt=2,
        retry_if_exception_type=(ValueError,),
    ).invoke(1)
except ValueError:
    pass

assert count == 2

map

map() -> Runnable[list[Input], list[Output]]

Return a new Runnable that maps a list of inputs to a list of outputs.

Calls invoke with each input.

RETURNS	DESCRIPTION
Runnable[list[Input], list[Output]]	A new Runnable that maps a list of inputs to a list of outputs.

Example

from langchain_core.runnables import RunnableLambda


def _lambda(x: int) -> int:
    return x + 1


runnable = RunnableLambda(_lambda)
print(runnable.map().invoke([1, 2, 3]))  # [2, 3, 4]

with_fallbacks

with_fallbacks(
    fallbacks: Sequence[Runnable[Input, Output]],
    *,
    exceptions_to_handle: tuple[type[BaseException], ...] = (Exception,),
    exception_key: str | None = None,
) -> RunnableWithFallbacks[Input, Output]

Add fallbacks to a Runnable, returning a new Runnable.

The new Runnable will try the original Runnable, and then each fallback in order, upon failures.

PARAMETER	DESCRIPTION
fallbacks	A sequence of runnables to try if the original Runnable fails. TYPE: Sequence[Runnable[Input, Output]]
exceptions_to_handle	A tuple of exception types to handle. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
exception_key	If string is specified then handled exceptions will be passed to fallbacks as part of the input under the specified key. If None, exceptions will not be passed to fallbacks. If used, the base Runnable and its fallbacks must accept a dictionary as input. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableWithFallbacks[Input, Output]	A new Runnable that will try the original Runnable, and then each Fallback in order, upon failures.

Example

from typing import Iterator

from langchain_core.runnables import RunnableGenerator


def _generate_immediate_error(input: Iterator) -> Iterator[str]:
    raise ValueError()
    yield ""


def _generate(input: Iterator) -> Iterator[str]:
    yield from "foo bar"


runnable = RunnableGenerator(_generate_immediate_error).with_fallbacks(
    [RunnableGenerator(_generate)]
)
print("".join(runnable.stream({})))  # foo bar

PARAMETER	DESCRIPTION
fallbacks	A sequence of runnables to try if the original Runnable fails. TYPE: Sequence[Runnable[Input, Output]]
exceptions_to_handle	A tuple of exception types to handle. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
exception_key	If string is specified then handled exceptions will be passed to fallbacks as part of the input under the specified key. If None, exceptions will not be passed to fallbacks. If used, the base Runnable and its fallbacks must accept a dictionary as input. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableWithFallbacks[Input, Output]	A new Runnable that will try the original Runnable, and then each Fallback in order, upon failures.

as_tool

as_tool(
    args_schema: type[BaseModel] | None = None,
    *,
    name: str | None = None,
    description: str | None = None,
    arg_types: dict[str, type] | None = None,
) -> BaseTool

Create a BaseTool from a Runnable.

as_tool will instantiate a BaseTool with a name, description, and args_schema from a Runnable. Where possible, schemas are inferred from runnable.get_input_schema.

Alternatively (e.g., if the Runnable takes a dict as input and the specific dict keys are not typed), the schema can be specified directly with args_schema.

You can also pass arg_types to just specify the required arguments and their types.

PARAMETER	DESCRIPTION
args_schema	The schema for the tool. TYPE: type[BaseModel] | None DEFAULT: None
name	The name of the tool. TYPE: str | None DEFAULT: None
description	The description of the tool. TYPE: str | None DEFAULT: None
arg_types	A dictionary of argument names to types. TYPE: dict[str, type] | None DEFAULT: None

RETURNS	DESCRIPTION
BaseTool	A BaseTool instance.

Typed dict input:

from typing_extensions import TypedDict
from langchain_core.runnables import RunnableLambda


class Args(TypedDict):
    a: int
    b: list[int]


def f(x: Args) -> str:
    return str(x["a"] * max(x["b"]))


runnable = RunnableLambda(f)
as_tool = runnable.as_tool()
as_tool.invoke({"a": 3, "b": [1, 2]})

dict input, specifying schema via args_schema:

from typing import Any
from pydantic import BaseModel, Field
from langchain_core.runnables import RunnableLambda

def f(x: dict[str, Any]) -> str:
    return str(x["a"] * max(x["b"]))

class FSchema(BaseModel):
    """Apply a function to an integer and list of integers."""

    a: int = Field(..., description="Integer")
    b: list[int] = Field(..., description="List of ints")

runnable = RunnableLambda(f)
as_tool = runnable.as_tool(FSchema)
as_tool.invoke({"a": 3, "b": [1, 2]})

dict input, specifying schema via arg_types:

from typing import Any
from langchain_core.runnables import RunnableLambda


def f(x: dict[str, Any]) -> str:
    return str(x["a"] * max(x["b"]))


runnable = RunnableLambda(f)
as_tool = runnable.as_tool(arg_types={"a": int, "b": list[int]})
as_tool.invoke({"a": 3, "b": [1, 2]})

str input:

from langchain_core.runnables import RunnableLambda


def f(x: str) -> str:
    return x + "a"


def g(x: str) -> str:
    return x + "z"


runnable = RunnableLambda(f) | g
as_tool = runnable.as_tool()
as_tool.invoke("b")

__init__

__init__(**kwargs: Any) -> None

Initialize the tool.

RAISES	DESCRIPTION
TypeError	If args_schema is not a subclass of pydantic BaseModel or dict.

is_lc_serializable classmethod

is_lc_serializable() -> bool

Is this class serializable?

By design, even if a class inherits from Serializable, it is not serializable by default. This is to prevent accidental serialization of objects that should not be serialized.

RETURNS	DESCRIPTION
bool	Whether the class is serializable. Default is False.

get_lc_namespace classmethod

get_lc_namespace() -> list[str]

Get the namespace of the LangChain object.

For example, if the class is langchain.llms.openai.OpenAI, then the namespace is ["langchain", "llms", "openai"]

RETURNS	DESCRIPTION
list[str]	The namespace.

lc_id classmethod

lc_id() -> list[str]

Return a unique identifier for this class for serialization purposes.

The unique identifier is a list of strings that describes the path to the object.

For example, for the class langchain.llms.openai.OpenAI, the id is ["langchain", "llms", "openai", "OpenAI"].

to_json

to_json() -> SerializedConstructor | SerializedNotImplemented

Serialize the Runnable to JSON.

RETURNS	DESCRIPTION
SerializedConstructor | SerializedNotImplemented	A JSON-serializable representation of the Runnable.

to_json_not_implemented

to_json_not_implemented() -> SerializedNotImplemented

Serialize a "not implemented" object.

RETURNS	DESCRIPTION
SerializedNotImplemented	SerializedNotImplemented.

configurable_fields

configurable_fields(
    **kwargs: AnyConfigurableField,
) -> RunnableSerializable[Input, Output]

Configure particular Runnable fields at runtime.

PARAMETER	DESCRIPTION
**kwargs	A dictionary of ConfigurableField instances to configure. TYPE: AnyConfigurableField DEFAULT: {}

RAISES	DESCRIPTION
ValueError	If a configuration key is not found in the Runnable.

RETURNS	DESCRIPTION
RunnableSerializable[Input, Output]	A new Runnable with the fields configured.

from langchain_core.runnables import ConfigurableField
from langchain_openai import ChatOpenAI

model = ChatOpenAI(max_tokens=20).configurable_fields(
    max_tokens=ConfigurableField(
        id="output_token_number",
        name="Max tokens in the output",
        description="The maximum number of tokens in the output",
    )
)

# max_tokens = 20
print("max_tokens_20: ", model.invoke("tell me something about chess").content)

# max_tokens = 200
print(
    "max_tokens_200: ",
    model.with_config(configurable={"output_token_number": 200})
    .invoke("tell me something about chess")
    .content,
)

configurable_alternatives

configurable_alternatives(
    which: ConfigurableField,
    *,
    default_key: str = "default",
    prefix_keys: bool = False,
    **kwargs: Runnable[Input, Output] | Callable[[], Runnable[Input, Output]],
) -> RunnableSerializable[Input, Output]

Configure alternatives for Runnable objects that can be set at runtime.

PARAMETER	DESCRIPTION
which	The ConfigurableField instance that will be used to select the alternative. TYPE: ConfigurableField
default_key	The default key to use if no alternative is selected. TYPE: str DEFAULT: 'default'
prefix_keys	Whether to prefix the keys with the ConfigurableField id. TYPE: bool DEFAULT: False
**kwargs	A dictionary of keys to Runnable instances or callables that return Runnable instances. TYPE: Runnable[Input, Output] | Callable[[], Runnable[Input, Output]] DEFAULT: {}

RETURNS	DESCRIPTION
RunnableSerializable[Input, Output]	A new Runnable with the alternatives configured.

from langchain_anthropic import ChatAnthropic
from langchain_core.runnables.utils import ConfigurableField
from langchain_openai import ChatOpenAI

model = ChatAnthropic(
    model_name="claude-sonnet-4-5-20250929"
).configurable_alternatives(
    ConfigurableField(id="llm"),
    default_key="anthropic",
    openai=ChatOpenAI(),
)

# uses the default model ChatAnthropic
print(model.invoke("which organization created you?").content)

# uses ChatOpenAI
print(
    model.with_config(configurable={"llm": "openai"})
    .invoke("which organization created you?")
    .content
)

__init_subclass__

__init_subclass__(**kwargs: Any) -> None

Validate the tool class definition during subclass creation.

PARAMETER	DESCRIPTION
**kwargs	Additional keyword arguments passed to the parent class. TYPE: Any DEFAULT: {}

RAISES	DESCRIPTION
SchemaAnnotationError	If args_schema has incorrect type annotation.

run

run(
    tool_input: str | dict[str, Any],
    verbose: bool | None = None,
    start_color: str | None = "green",
    color: str | None = "green",
    callbacks: Callbacks = None,
    *,
    tags: list[str] | None = None,
    metadata: dict[str, Any] | None = None,
    run_name: str | None = None,
    run_id: UUID | None = None,
    config: RunnableConfig | None = None,
    tool_call_id: str | None = None,
    **kwargs: Any,
) -> Any

Run the tool.

PARAMETER	DESCRIPTION
tool_input	The input to the tool. TYPE: str | dict[str, Any]
verbose	Whether to log the tool's progress. TYPE: bool | None DEFAULT: None
start_color	The color to use when starting the tool. TYPE: str | None DEFAULT: 'green'
color	The color to use when ending the tool. TYPE: str | None DEFAULT: 'green'
callbacks	Callbacks to be called during tool execution. TYPE: Callbacks DEFAULT: None
tags	Optional list of tags associated with the tool. TYPE: list[str] | None DEFAULT: None
metadata	Optional metadata associated with the tool. TYPE: dict[str, Any] | None DEFAULT: None
run_name	The name of the run. TYPE: str | None DEFAULT: None
run_id	The id of the run. TYPE: UUID | None DEFAULT: None
config	The configuration for the tool. TYPE: RunnableConfig | None DEFAULT: None
tool_call_id	The id of the tool call. TYPE: str | None DEFAULT: None
**kwargs	Keyword arguments to be passed to tool callbacks (event handler) TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Any	The output of the tool.

RAISES	DESCRIPTION
ToolException	If an error occurs during tool execution.

arun async

arun(
    tool_input: str | dict,
    verbose: bool | None = None,
    start_color: str | None = "green",
    color: str | None = "green",
    callbacks: Callbacks = None,
    *,
    tags: list[str] | None = None,
    metadata: dict[str, Any] | None = None,
    run_name: str | None = None,
    run_id: UUID | None = None,
    config: RunnableConfig | None = None,
    tool_call_id: str | None = None,
    **kwargs: Any,
) -> Any

Run the tool asynchronously.

PARAMETER	DESCRIPTION
tool_input	The input to the tool. TYPE: str | dict
verbose	Whether to log the tool's progress. TYPE: bool | None DEFAULT: None
start_color	The color to use when starting the tool. TYPE: str | None DEFAULT: 'green'
color	The color to use when ending the tool. TYPE: str | None DEFAULT: 'green'
callbacks	Callbacks to be called during tool execution. TYPE: Callbacks DEFAULT: None
tags	Optional list of tags associated with the tool. TYPE: list[str] | None DEFAULT: None
metadata	Optional metadata associated with the tool. TYPE: dict[str, Any] | None DEFAULT: None
run_name	The name of the run. TYPE: str | None DEFAULT: None
run_id	The id of the run. TYPE: UUID | None DEFAULT: None
config	The configuration for the tool. TYPE: RunnableConfig | None DEFAULT: None
tool_call_id	The id of the tool call. TYPE: str | None DEFAULT: None
**kwargs	Keyword arguments to be passed to tool callbacks TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Any	The output of the tool.

RAISES	DESCRIPTION
ToolException	If an error occurs during tool execution.

validate_environment classmethod

validate_environment(values: dict) -> Any

Validate the environment.

ExaSearchResults

Bases: BaseTool

Exa Search tool.

Setup

Install langchain-exa and set environment variable EXA_API_KEY.

pip install -U langchain-exa
export EXA_API_KEY="your-api-key"

Instantiation

from langchain-exa import ExaSearchResults

tool = ExaSearchResults()

Invocation with args

tool.invoke({"query": "what is the weather in SF", "num_results": 1})

SearchResponse(
    results=[
        Result(
            url="https://www.wunderground.com/weather/37.8,-122.4",
            id="https://www.wunderground.com/weather/37.8,-122.4",
            title="San Francisco, CA Weather Conditionsstar_ratehome",
            score=0.1843988299369812,
            published_date="2023-02-23T01:17:06.594Z",
            author=None,
            text="The time period when the sun is no more than 6 degrees below the horizon at either sunrise or sunset. The horizon should be clearly defined and the brightest stars should be visible under good atmospheric conditions (i.e. no moonlight, or other lights). One still should be able to carry on ordinary outdoor activities. The time period when the sun is between 6 and 12 degrees below the horizon at either sunrise or sunset. The horizon is well defined and the outline of objects might be visible without artificial light. Ordinary outdoor activities are not possible at this time without extra illumination. The time period when the sun is between 12 and 18 degrees below the horizon at either sunrise or sunset. The sun does not contribute to the illumination of the sky before this time in the morning, or after this time in the evening. In the beginning of morning astronomical twilight and at the end of astronomical twilight in the evening, sky illumination is very faint, and might be undetectable. The time of Civil Sunset minus the time of Civil Sunrise. The time of Actual Sunset minus the time of Actual Sunrise. The change in length of daylight between today and tomorrow is also listed when available.",
            highlights=None,
            highlight_scores=None,
            summary=None,
        )
    ],
    autoprompt_string=None,
)

Invocation with ToolCall:

```python
tool.invoke(
    {
        "args": {"query": "what is the weather in SF", "num_results": 1},
        "id": "1",
        "name": tool.name,
        "type": "tool_call",
    }
)
```

```python
ToolMessage(
    content="Title: San Francisco, CA Weather Conditionsstar_ratehome\nURL: https://www.wunderground.com/weather/37.8,-122.4\nID: https://www.wunderground.com/weather/37.8,-122.4\nScore: 0.1843988299369812\nPublished Date: 2023-02-23T01:17:06.594Z\nAuthor: None\nText: The time period when the sun is no more than 6 degrees below the horizon at either sunrise or sunset. The horizon should be clearly defined and the brightest stars should be visible under good atmospheric conditions (i.e. no moonlight, or other lights). One still should be able to carry on ordinary outdoor activities. The time period when the sun is between 6 and 12 degrees below the horizon at either sunrise or sunset. The horizon is well defined and the outline of objects might be visible without artificial light. Ordinary outdoor activities are not possible at this time without extra illumination. The time period when the sun is between 12 and 18 degrees below the horizon at either sunrise or sunset. The sun does not contribute to the illumination of the sky before this time in the morning, or after this time in the evening. In the beginning of morning astronomical twilight and at the end of astronomical twilight in the evening, sky illumination is very faint, and might be undetectable. The time of Civil Sunset minus the time of Civil Sunrise. The time of Actual Sunset minus the time of Actual Sunrise. The change in length of daylight between today and tomorrow is also listed when available.\nHighlights: None\nHighlight Scores: None\nSummary: None\n",
    name="exa_search_results_json",
    tool_call_id="1",
)
```

METHOD	DESCRIPTION
get_name	Get the name of the Runnable.
get_input_schema	The tool's input schema.
get_input_jsonschema	Get a JSON schema that represents the input to the Runnable.
get_output_schema	Get a Pydantic model that can be used to validate output to the Runnable.
get_output_jsonschema	Get a JSON schema that represents the output of the Runnable.
config_schema	The type of config this Runnable accepts specified as a Pydantic model.
get_config_jsonschema	Get a JSON schema that represents the config of the Runnable.
get_graph	Return a graph representation of this Runnable.
get_prompts	Return a list of prompts used by this Runnable.
__or__	Runnable "or" operator.
__ror__	Runnable "reverse-or" operator.
pipe	Pipe Runnable objects.
pick	Pick keys from the output dict of this Runnable.
assign	Assigns new fields to the dict output of this Runnable.
invoke	Transform a single input into an output.
ainvoke	Transform a single input into an output.
batch	Default implementation runs invoke in parallel using a thread pool executor.
batch_as_completed	Run invoke in parallel on a list of inputs.
abatch	Default implementation runs ainvoke in parallel using asyncio.gather.
abatch_as_completed	Run ainvoke in parallel on a list of inputs.
stream	Default implementation of stream, which calls invoke.
astream	Default implementation of astream, which calls ainvoke.
astream_log	Stream all output from a Runnable, as reported to the callback system.
astream_events	Generate a stream of events.
transform	Transform inputs to outputs.
atransform	Transform inputs to outputs.
bind	Bind arguments to a Runnable, returning a new Runnable.
with_config	Bind config to a Runnable, returning a new Runnable.
with_listeners	Bind lifecycle listeners to a Runnable, returning a new Runnable.
with_alisteners	Bind async lifecycle listeners to a Runnable.
with_types	Bind input and output types to a Runnable, returning a new Runnable.
with_retry	Create a new Runnable that retries the original Runnable on exceptions.
map	Return a new Runnable that maps a list of inputs to a list of outputs.
with_fallbacks	Add fallbacks to a Runnable, returning a new Runnable.
as_tool	Create a BaseTool from a Runnable.
__init__	Initialize the tool.
is_lc_serializable	Is this class serializable?
get_lc_namespace	Get the namespace of the LangChain object.
lc_id	Return a unique identifier for this class for serialization purposes.
to_json	Serialize the Runnable to JSON.
to_json_not_implemented	Serialize a "not implemented" object.
configurable_fields	Configure particular Runnable fields at runtime.
configurable_alternatives	Configure alternatives for Runnable objects that can be set at runtime.
__init_subclass__	Validate the tool class definition during subclass creation.
run	Run the tool.
arun	Run the tool asynchronously.
validate_environment	Validate the environment.

InputType property

InputType: type[Input]

Input type.

The type of input this Runnable accepts specified as a type annotation.

RAISES	DESCRIPTION
TypeError	If the input type cannot be inferred.

OutputType property

OutputType: type[Output]

Output Type.

The type of output this Runnable produces specified as a type annotation.

RAISES	DESCRIPTION
TypeError	If the output type cannot be inferred.

input_schema property

input_schema: type[BaseModel]

The type of input this Runnable accepts specified as a Pydantic model.

output_schema property

output_schema: type[BaseModel]

Output schema.

The type of output this Runnable produces specified as a Pydantic model.

config_specs property

config_specs: list[ConfigurableFieldSpec]

List configurable fields for this Runnable.

lc_secrets property

lc_secrets: dict[str, str]

A map of constructor argument names to secret ids.

For example, {"openai_api_key": "OPENAI_API_KEY"}

lc_attributes property

lc_attributes: dict

List of attribute names that should be included in the serialized kwargs.

These attributes must be accepted by the constructor.

Default is an empty dictionary.

args_schema class-attribute instance-attribute

args_schema: Annotated[ArgsSchema | None, SkipValidation()] = Field(
    default=None, description="The tool schema."
)

Pydantic model class to validate and parse the tool's input arguments.

Args schema should be either:

• A subclass of pydantic.BaseModel.
• A subclass of pydantic.v1.BaseModel if accessing v1 namespace in pydantic 2
• A JSON schema dict

return_direct class-attribute instance-attribute

return_direct: bool = False

Whether to return the tool's output directly.

Setting this to True means that after the tool is called, the AgentExecutor will stop looping.

verbose class-attribute instance-attribute

verbose: bool = False

Whether to log the tool's progress.

callbacks class-attribute instance-attribute

callbacks: Callbacks = Field(default=None, exclude=True)

Callbacks to be called during tool execution.

tags class-attribute instance-attribute

tags: list[str] | None = None

Optional list of tags associated with the tool.

These tags will be associated with each call to this tool, and passed as arguments to the handlers defined in callbacks.

You can use these to, e.g., identify a specific instance of a tool with its use case.

metadata class-attribute instance-attribute

metadata: dict[str, Any] | None = None

Optional metadata associated with the tool.

This metadata will be associated with each call to this tool, and passed as arguments to the handlers defined in callbacks.

You can use these to, e.g., identify a specific instance of a tool with its use case.

handle_tool_error class-attribute instance-attribute

handle_tool_error: bool | str | Callable[[ToolException], str] | None = False

Handle the content of the ToolException thrown.

handle_validation_error class-attribute instance-attribute

handle_validation_error: (
    bool | str | Callable[[ValidationError | ValidationError], str] | None
) = False

Handle the content of the ValidationError thrown.

response_format class-attribute instance-attribute

response_format: Literal['content', 'content_and_artifact'] = 'content'

The tool response format.

If 'content' then the output of the tool is interpreted as the contents of a ToolMessage. If 'content_and_artifact' then the output is expected to be a two-tuple corresponding to the (content, artifact) of a ToolMessage.

is_single_input property

is_single_input: bool

Check if the tool accepts only a single input argument.

RETURNS	DESCRIPTION
bool	True if the tool has only one input argument, False otherwise.

args property

args: dict

Get the tool's input arguments schema.

RETURNS	DESCRIPTION
dict	dict containing the tool's argument properties.

tool_call_schema property

tool_call_schema: ArgsSchema

Get the schema for tool calls, excluding injected arguments.

RETURNS	DESCRIPTION
ArgsSchema	The schema that should be used for tool calls from language models.

name class-attribute instance-attribute

name: str = 'exa_search_results_json'

The unique name of the tool that clearly communicates its purpose.

description class-attribute instance-attribute

description: str = "A wrapper around Exa Search. Input should be an Exa-optimized query. Output is a JSON array of the query results"

Used to tell the model how/when/why to use the tool.

You can provide few-shot examples as a part of the description.

get_name

get_name(suffix: str | None = None, *, name: str | None = None) -> str

Get the name of the Runnable.

PARAMETER	DESCRIPTION
suffix	An optional suffix to append to the name. TYPE: str | None DEFAULT: None
name	An optional name to use instead of the Runnable's name. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
str	The name of the Runnable.

get_input_schema

get_input_schema(config: RunnableConfig | None = None) -> type[BaseModel]

The tool's input schema.

PARAMETER	DESCRIPTION
config	The configuration for the tool. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	The input schema for the tool.

get_input_jsonschema

get_input_jsonschema(config: RunnableConfig | None = None) -> dict[str, Any]

Get a JSON schema that represents the input to the Runnable.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the input to the Runnable.

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


runnable = RunnableLambda(add_one)

print(runnable.get_input_jsonschema())

Added in langchain-core 0.3.0

get_output_schema

get_output_schema(config: RunnableConfig | None = None) -> type[BaseModel]

Get a Pydantic model that can be used to validate output to the Runnable.

Runnable objects that leverage the configurable_fields and configurable_alternatives methods will have a dynamic output schema that depends on which configuration the Runnable is invoked with.

This method allows to get an output schema for a specific configuration.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	A Pydantic model that can be used to validate output.

get_output_jsonschema

get_output_jsonschema(config: RunnableConfig | None = None) -> dict[str, Any]

Get a JSON schema that represents the output of the Runnable.

PARAMETER	DESCRIPTION
config	A config to use when generating the schema. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the output of the Runnable.

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


runnable = RunnableLambda(add_one)

print(runnable.get_output_jsonschema())

Added in langchain-core 0.3.0

config_schema

config_schema(*, include: Sequence[str] | None = None) -> type[BaseModel]

The type of config this Runnable accepts specified as a Pydantic model.

To mark a field as configurable, see the configurable_fields and configurable_alternatives methods.

PARAMETER	DESCRIPTION
include	A list of fields to include in the config schema. TYPE: Sequence[str] | None DEFAULT: None

RETURNS	DESCRIPTION
type[BaseModel]	A Pydantic model that can be used to validate config.

get_config_jsonschema

get_config_jsonschema(*, include: Sequence[str] | None = None) -> dict[str, Any]

Get a JSON schema that represents the config of the Runnable.

PARAMETER	DESCRIPTION
include	A list of fields to include in the config schema. TYPE: Sequence[str] | None DEFAULT: None

RETURNS	DESCRIPTION
dict[str, Any]	A JSON schema that represents the config of the Runnable.

Added in langchain-core 0.3.0

get_graph

get_graph(config: RunnableConfig | None = None) -> Graph

Return a graph representation of this Runnable.

get_prompts

get_prompts(config: RunnableConfig | None = None) -> list[BasePromptTemplate]

Return a list of prompts used by this Runnable.

__or__

__or__(
    other: Runnable[Any, Other]
    | Callable[[Iterator[Any]], Iterator[Other]]
    | Callable[[AsyncIterator[Any]], AsyncIterator[Other]]
    | Callable[[Any], Other]
    | Mapping[str, Runnable[Any, Other] | Callable[[Any], Other] | Any],
) -> RunnableSerializable[Input, Other]

Runnable "or" operator.

Compose this Runnable with another object to create a RunnableSequence.

PARAMETER	DESCRIPTION
other	Another Runnable or a Runnable-like object. TYPE: Runnable[Any, Other] | Callable[[Iterator[Any]], Iterator[Other]] | Callable[[AsyncIterator[Any]], AsyncIterator[Other]] | Callable[[Any], Other] | Mapping[str, Runnable[Any, Other] | Callable[[Any], Other] | Any]

RETURNS	DESCRIPTION
RunnableSerializable[Input, Other]	A new Runnable.

__ror__

__ror__(
    other: Runnable[Other, Any]
    | Callable[[Iterator[Other]], Iterator[Any]]
    | Callable[[AsyncIterator[Other]], AsyncIterator[Any]]
    | Callable[[Other], Any]
    | Mapping[str, Runnable[Other, Any] | Callable[[Other], Any] | Any],
) -> RunnableSerializable[Other, Output]

Runnable "reverse-or" operator.

Compose this Runnable with another object to create a RunnableSequence.

PARAMETER	DESCRIPTION
other	Another Runnable or a Runnable-like object. TYPE: Runnable[Other, Any] | Callable[[Iterator[Other]], Iterator[Any]] | Callable[[AsyncIterator[Other]], AsyncIterator[Any]] | Callable[[Other], Any] | Mapping[str, Runnable[Other, Any] | Callable[[Other], Any] | Any]

RETURNS	DESCRIPTION
RunnableSerializable[Other, Output]	A new Runnable.

pipe

pipe(
    *others: Runnable[Any, Other] | Callable[[Any], Other], name: str | None = None
) -> RunnableSerializable[Input, Other]

Pipe Runnable objects.

Compose this Runnable with Runnable-like objects to make a RunnableSequence.

Equivalent to RunnableSequence(self, *others) or self | others[0] | ...

Example

from langchain_core.runnables import RunnableLambda


def add_one(x: int) -> int:
    return x + 1


def mul_two(x: int) -> int:
    return x * 2


runnable_1 = RunnableLambda(add_one)
runnable_2 = RunnableLambda(mul_two)
sequence = runnable_1.pipe(runnable_2)
# Or equivalently:
# sequence = runnable_1 | runnable_2
# sequence = RunnableSequence(first=runnable_1, last=runnable_2)
sequence.invoke(1)
await sequence.ainvoke(1)
# -> 4

sequence.batch([1, 2, 3])
await sequence.abatch([1, 2, 3])
# -> [4, 6, 8]

PARAMETER	DESCRIPTION
*others	Other Runnable or Runnable-like objects to compose TYPE: Runnable[Any, Other] | Callable[[Any], Other] DEFAULT: ()
name	An optional name for the resulting RunnableSequence. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableSerializable[Input, Other]	A new Runnable.

pick

pick(keys: str | list[str]) -> RunnableSerializable[Any, Any]

Pick keys from the output dict of this Runnable.

Pick a single key:

import json

from langchain_core.runnables import RunnableLambda, RunnableMap

as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)
chain = RunnableMap(str=as_str, json=as_json)

chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3]}

json_only_chain = chain.pick("json")
json_only_chain.invoke("[1, 2, 3]")
# -> [1, 2, 3]

Pick a list of keys:

from typing import Any

import json

from langchain_core.runnables import RunnableLambda, RunnableMap

as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)


def as_bytes(x: Any) -> bytes:
    return bytes(x, "utf-8")


chain = RunnableMap(str=as_str, json=as_json, bytes=RunnableLambda(as_bytes))

chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3], "bytes": b"[1, 2, 3]"}

json_and_bytes_chain = chain.pick(["json", "bytes"])
json_and_bytes_chain.invoke("[1, 2, 3]")
# -> {"json": [1, 2, 3], "bytes": b"[1, 2, 3]"}

PARAMETER	DESCRIPTION
keys	A key or list of keys to pick from the output dict. TYPE: str | list[str]

RETURNS	DESCRIPTION
RunnableSerializable[Any, Any]	a new Runnable.

assign

assign(
    **kwargs: Runnable[dict[str, Any], Any]
    | Callable[[dict[str, Any]], Any]
    | Mapping[str, Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any]],
) -> RunnableSerializable[Any, Any]

Assigns new fields to the dict output of this Runnable.

from langchain_core.language_models.fake import FakeStreamingListLLM
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import SystemMessagePromptTemplate
from langchain_core.runnables import Runnable
from operator import itemgetter

prompt = (
    SystemMessagePromptTemplate.from_template("You are a nice assistant.")
    + "{question}"
)
model = FakeStreamingListLLM(responses=["foo-lish"])

chain: Runnable = prompt | model | {"str": StrOutputParser()}

chain_with_assign = chain.assign(hello=itemgetter("str") | model)

print(chain_with_assign.input_schema.model_json_schema())
# {'title': 'PromptInput', 'type': 'object', 'properties':
{'question': {'title': 'Question', 'type': 'string'}}}
print(chain_with_assign.output_schema.model_json_schema())
# {'title': 'RunnableSequenceOutput', 'type': 'object', 'properties':
{'str': {'title': 'Str',
'type': 'string'}, 'hello': {'title': 'Hello', 'type': 'string'}}}

PARAMETER	DESCRIPTION
**kwargs	A mapping of keys to Runnable or Runnable-like objects that will be invoked with the entire output dict of this Runnable. TYPE: Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any] | Mapping[str, Runnable[dict[str, Any], Any] | Callable[[dict[str, Any]], Any]] DEFAULT: {}

RETURNS	DESCRIPTION
RunnableSerializable[Any, Any]	A new Runnable.

invoke

invoke(
    input: str | dict | ToolCall, config: RunnableConfig | None = None, **kwargs: Any
) -> Any

Transform a single input into an output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
Output	The output of the Runnable.

ainvoke async

ainvoke(
    input: str | dict | ToolCall, config: RunnableConfig | None = None, **kwargs: Any
) -> Any

Transform a single input into an output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | None DEFAULT: None

RETURNS	DESCRIPTION
Output	The output of the Runnable.

batch

batch(
    inputs: list[Input],
    config: RunnableConfig | list[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> list[Output]

Default implementation runs invoke in parallel using a thread pool executor.

The default implementation of batch works well for IO bound runnables.

Subclasses must override this method if they can batch more efficiently; e.g., if the underlying Runnable uses an API which supports a batch mode.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: list[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | list[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

RETURNS	DESCRIPTION
list[Output]	A list of outputs from the Runnable.

batch_as_completed

batch_as_completed(
    inputs: Sequence[Input],
    config: RunnableConfig | Sequence[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> Iterator[tuple[int, Output | Exception]]

Run invoke in parallel on a list of inputs.

Yields results as they complete.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: Sequence[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | Sequence[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
tuple[int, Output | Exception]	Tuples of the index of the input and the output from the Runnable.

abatch async

abatch(
    inputs: list[Input],
    config: RunnableConfig | list[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> list[Output]

Default implementation runs ainvoke in parallel using asyncio.gather.

The default implementation of batch works well for IO bound runnables.

Subclasses must override this method if they can batch more efficiently; e.g., if the underlying Runnable uses an API which supports a batch mode.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: list[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | list[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

RETURNS	DESCRIPTION
list[Output]	A list of outputs from the Runnable.

abatch_as_completed async

abatch_as_completed(
    inputs: Sequence[Input],
    config: RunnableConfig | Sequence[RunnableConfig] | None = None,
    *,
    return_exceptions: bool = False,
    **kwargs: Any | None,
) -> AsyncIterator[tuple[int, Output | Exception]]

Run ainvoke in parallel on a list of inputs.

Yields results as they complete.

PARAMETER	DESCRIPTION
inputs	A list of inputs to the Runnable. TYPE: Sequence[Input]
config	A config to use when invoking the Runnable. The config supports standard keys like 'tags', 'metadata' for tracing purposes, 'max_concurrency' for controlling how much work to do in parallel, and other keys. Please refer to RunnableConfig for more details. TYPE: RunnableConfig | Sequence[RunnableConfig] | None DEFAULT: None
return_exceptions	Whether to return exceptions instead of raising them. TYPE: bool DEFAULT: False
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[tuple[int, Output | Exception]]	A tuple of the index of the input and the output from the Runnable.

stream

stream(
    input: Input, config: RunnableConfig | None = None, **kwargs: Any | None
) -> Iterator[Output]

Default implementation of stream, which calls invoke.

Subclasses must override this method if they support streaming output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
Output	The output of the Runnable.

astream async

astream(
    input: Input, config: RunnableConfig | None = None, **kwargs: Any | None
) -> AsyncIterator[Output]

Default implementation of astream, which calls ainvoke.

Subclasses must override this method if they support streaming output.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Input
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[Output]	The output of the Runnable.

astream_log async

astream_log(
    input: Any,
    config: RunnableConfig | None = None,
    *,
    diff: bool = True,
    with_streamed_output_list: bool = True,
    include_names: Sequence[str] | None = None,
    include_types: Sequence[str] | None = None,
    include_tags: Sequence[str] | None = None,
    exclude_names: Sequence[str] | None = None,
    exclude_types: Sequence[str] | None = None,
    exclude_tags: Sequence[str] | None = None,
    **kwargs: Any,
) -> AsyncIterator[RunLogPatch] | AsyncIterator[RunLog]

Stream all output from a Runnable, as reported to the callback system.

This includes all inner runs of LLMs, Retrievers, Tools, etc.

Output is streamed as Log objects, which include a list of Jsonpatch ops that describe how the state of the run has changed in each step, and the final state of the run.

The Jsonpatch ops can be applied in order to construct state.

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Any
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
diff	Whether to yield diffs between each step or the current state. TYPE: bool DEFAULT: True
with_streamed_output_list	Whether to yield the streamed_output list. TYPE: bool DEFAULT: True
include_names	Only include logs with these names. TYPE: Sequence[str] | None DEFAULT: None
include_types	Only include logs with these types. TYPE: Sequence[str] | None DEFAULT: None
include_tags	Only include logs with these tags. TYPE: Sequence[str] | None DEFAULT: None
exclude_names	Exclude logs with these names. TYPE: Sequence[str] | None DEFAULT: None
exclude_types	Exclude logs with these types. TYPE: Sequence[str] | None DEFAULT: None
exclude_tags	Exclude logs with these tags. TYPE: Sequence[str] | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[RunLogPatch] | AsyncIterator[RunLog]	A RunLogPatch or RunLog object.

astream_events async

astream_events(
    input: Any,
    config: RunnableConfig | None = None,
    *,
    version: Literal["v1", "v2"] = "v2",
    include_names: Sequence[str] | None = None,
    include_types: Sequence[str] | None = None,
    include_tags: Sequence[str] | None = None,
    exclude_names: Sequence[str] | None = None,
    exclude_types: Sequence[str] | None = None,
    exclude_tags: Sequence[str] | None = None,
    **kwargs: Any,
) -> AsyncIterator[StreamEvent]

Generate a stream of events.

Use to create an iterator over StreamEvent that provide real-time information about the progress of the Runnable, including StreamEvent from intermediate results.

A StreamEvent is a dictionary with the following schema:

• event: Event names are of the format: on_[runnable_type]_(start|stream|end).
• name: The name of the Runnable that generated the event.
• run_id: Randomly generated ID associated with the given execution of the Runnable that emitted the event. A child Runnable that gets invoked as part of the execution of a parent Runnable is assigned its own unique ID.
• parent_ids: The IDs of the parent runnables that generated the event. The root Runnable will have an empty list. The order of the parent IDs is from the root to the immediate parent. Only available for v2 version of the API. The v1 version of the API will return an empty list.
• tags: The tags of the Runnable that generated the event.
• metadata: The metadata of the Runnable that generated the event.
• data: The data associated with the event. The contents of this field depend on the type of event. See the table below for more details.

Below is a table that illustrates some events that might be emitted by various chains. Metadata fields have been omitted from the table for brevity. Chain definitions have been included after the table.

Note

This reference table is for the v2 version of the schema.

event	name	chunk	input	output
on_chat_model_start	'[model name]'		{"messages": [[SystemMessage, HumanMessage]]}
on_chat_model_stream	'[model name]'	AIMessageChunk(content="hello")
on_chat_model_end	'[model name]'		{"messages": [[SystemMessage, HumanMessage]]}	AIMessageChunk(content="hello world")
on_llm_start	'[model name]'		{'input': 'hello'}
on_llm_stream	'[model name]'	'Hello'
on_llm_end	'[model name]'		'Hello human!'
on_chain_start	'format_docs'
on_chain_stream	'format_docs'	'hello world!, goodbye world!'
on_chain_end	'format_docs'		[Document(...)]	'hello world!, goodbye world!'
on_tool_start	'some_tool'		{"x": 1, "y": "2"}
on_tool_end	'some_tool'			{"x": 1, "y": "2"}
on_retriever_start	'[retriever name]'		{"query": "hello"}
on_retriever_end	'[retriever name]'		{"query": "hello"}	[Document(...), ..]
on_prompt_start	'[template_name]'		{"question": "hello"}
on_prompt_end	'[template_name]'		{"question": "hello"}	ChatPromptValue(messages: [SystemMessage, ...])

In addition to the standard events, users can also dispatch custom events (see example below).

Custom events will be only be surfaced with in the v2 version of the API!

A custom event has following format:

Attribute	Type	Description
name	str	A user defined name for the event.
data	Any	The data associated with the event. This can be anything, though we suggest making it JSON serializable.

Here are declarations associated with the standard events shown above:

format_docs:

def format_docs(docs: list[Document]) -> str:
    '''Format the docs.'''
    return ", ".join([doc.page_content for doc in docs])


format_docs = RunnableLambda(format_docs)

some_tool:

@tool
def some_tool(x: int, y: str) -> dict:
    '''Some_tool.'''
    return {"x": x, "y": y}

prompt:

template = ChatPromptTemplate.from_messages(
    [
        ("system", "You are Cat Agent 007"),
        ("human", "{question}"),
    ]
).with_config({"run_name": "my_template", "tags": ["my_template"]})

For instance:

from langchain_core.runnables import RunnableLambda


async def reverse(s: str) -> str:
    return s[::-1]


chain = RunnableLambda(func=reverse)

events = [event async for event in chain.astream_events("hello", version="v2")]

# Will produce the following events
# (run_id, and parent_ids has been omitted for brevity):
[
    {
        "data": {"input": "hello"},
        "event": "on_chain_start",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
    {
        "data": {"chunk": "olleh"},
        "event": "on_chain_stream",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
    {
        "data": {"output": "olleh"},
        "event": "on_chain_end",
        "metadata": {},
        "name": "reverse",
        "tags": [],
    },
]

Example: Dispatch Custom Event

from langchain_core.callbacks.manager import (
    adispatch_custom_event,
)
from langchain_core.runnables import RunnableLambda, RunnableConfig
import asyncio


async def slow_thing(some_input: str, config: RunnableConfig) -> str:
    """Do something that takes a long time."""
    await asyncio.sleep(1) # Placeholder for some slow operation
    await adispatch_custom_event(
        "progress_event",
        {"message": "Finished step 1 of 3"},
        config=config # Must be included for python < 3.10
    )
    await asyncio.sleep(1) # Placeholder for some slow operation
    await adispatch_custom_event(
        "progress_event",
        {"message": "Finished step 2 of 3"},
        config=config # Must be included for python < 3.10
    )
    await asyncio.sleep(1) # Placeholder for some slow operation
    return "Done"

slow_thing = RunnableLambda(slow_thing)

async for event in slow_thing.astream_events("some_input", version="v2"):
    print(event)

PARAMETER	DESCRIPTION
input	The input to the Runnable. TYPE: Any
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
version	The version of the schema to use either 'v2' or 'v1'. Users should use 'v2'. 'v1' is for backwards compatibility and will be deprecated in 0.4.0. No default will be assigned until the API is stabilized. custom events will only be surfaced in 'v2'. TYPE: Literal['v1', 'v2'] DEFAULT: 'v2'
include_names	Only include events from Runnable objects with matching names. TYPE: Sequence[str] | None DEFAULT: None
include_types	Only include events from Runnable objects with matching types. TYPE: Sequence[str] | None DEFAULT: None
include_tags	Only include events from Runnable objects with matching tags. TYPE: Sequence[str] | None DEFAULT: None
exclude_names	Exclude events from Runnable objects with matching names. TYPE: Sequence[str] | None DEFAULT: None
exclude_types	Exclude events from Runnable objects with matching types. TYPE: Sequence[str] | None DEFAULT: None
exclude_tags	Exclude events from Runnable objects with matching tags. TYPE: Sequence[str] | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. These will be passed to astream_log as this implementation of astream_events is built on top of astream_log. TYPE: Any DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[StreamEvent]	An async stream of StreamEvent.

RAISES	DESCRIPTION
NotImplementedError	If the version is not 'v1' or 'v2'.

transform

transform(
    input: Iterator[Input], config: RunnableConfig | None = None, **kwargs: Any | None
) -> Iterator[Output]

Transform inputs to outputs.

Default implementation of transform, which buffers input and calls astream.

Subclasses must override this method if they can start producing output while input is still being generated.

PARAMETER	DESCRIPTION
input	An iterator of inputs to the Runnable. TYPE: Iterator[Input]
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
Output	The output of the Runnable.

atransform async

atransform(
    input: AsyncIterator[Input],
    config: RunnableConfig | None = None,
    **kwargs: Any | None,
) -> AsyncIterator[Output]

Transform inputs to outputs.

Default implementation of atransform, which buffers input and calls astream.

Subclasses must override this method if they can start producing output while input is still being generated.

PARAMETER	DESCRIPTION
input	An async iterator of inputs to the Runnable. TYPE: AsyncIterator[Input]
config	The config to use for the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any | None DEFAULT: {}

YIELDS	DESCRIPTION
AsyncIterator[Output]	The output of the Runnable.

bind

bind(**kwargs: Any) -> Runnable[Input, Output]

Bind arguments to a Runnable, returning a new Runnable.

Useful when a Runnable in a chain requires an argument that is not in the output of the previous Runnable or included in the user input.

PARAMETER	DESCRIPTION
**kwargs	The arguments to bind to the Runnable. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the arguments bound.

Example

from langchain_ollama import ChatOllama
from langchain_core.output_parsers import StrOutputParser

model = ChatOllama(model="llama3.1")

# Without bind
chain = model | StrOutputParser()

chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two three four five.'

# With bind
chain = model.bind(stop=["three"]) | StrOutputParser()

chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two'

with_config

with_config(
    config: RunnableConfig | None = None, **kwargs: Any
) -> Runnable[Input, Output]

Bind config to a Runnable, returning a new Runnable.

PARAMETER	DESCRIPTION
config	The config to bind to the Runnable. TYPE: RunnableConfig | None DEFAULT: None
**kwargs	Additional keyword arguments to pass to the Runnable. TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the config bound.

with_listeners

with_listeners(
    *,
    on_start: Callable[[Run], None]
    | Callable[[Run, RunnableConfig], None]
    | None = None,
    on_end: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None = None,
    on_error: Callable[[Run], None]
    | Callable[[Run, RunnableConfig], None]
    | None = None,
) -> Runnable[Input, Output]

Bind lifecycle listeners to a Runnable, returning a new Runnable.

The Run object contains information about the run, including its id, type, input, output, error, start_time, end_time, and any tags or metadata added to the run.

PARAMETER	DESCRIPTION
on_start	Called before the Runnable starts running, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None
on_end	Called after the Runnable finishes running, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None
on_error	Called if the Runnable throws an error, with the Run object. TYPE: Callable[[Run], None] | Callable[[Run, RunnableConfig], None] | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the listeners bound.

Example

from langchain_core.runnables import RunnableLambda
from langchain_core.tracers.schemas import Run

import time


def test_runnable(time_to_sleep: int):
    time.sleep(time_to_sleep)


def fn_start(run_obj: Run):
    print("start_time:", run_obj.start_time)


def fn_end(run_obj: Run):
    print("end_time:", run_obj.end_time)


chain = RunnableLambda(test_runnable).with_listeners(
    on_start=fn_start, on_end=fn_end
)
chain.invoke(2)

with_alisteners

with_alisteners(
    *,
    on_start: AsyncListener | None = None,
    on_end: AsyncListener | None = None,
    on_error: AsyncListener | None = None,
) -> Runnable[Input, Output]

Bind async lifecycle listeners to a Runnable.

Returns a new Runnable.

The Run object contains information about the run, including its id, type, input, output, error, start_time, end_time, and any tags or metadata added to the run.

PARAMETER	DESCRIPTION
on_start	Called asynchronously before the Runnable starts running, with the Run object. TYPE: AsyncListener | None DEFAULT: None
on_end	Called asynchronously after the Runnable finishes running, with the Run object. TYPE: AsyncListener | None DEFAULT: None
on_error	Called asynchronously if the Runnable throws an error, with the Run object. TYPE: AsyncListener | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the listeners bound.

Example

from langchain_core.runnables import RunnableLambda, Runnable
from datetime import datetime, timezone
import time
import asyncio


def format_t(timestamp: float) -> str:
    return datetime.fromtimestamp(timestamp, tz=timezone.utc).isoformat()


async def test_runnable(time_to_sleep: int):
    print(f"Runnable[{time_to_sleep}s]: starts at {format_t(time.time())}")
    await asyncio.sleep(time_to_sleep)
    print(f"Runnable[{time_to_sleep}s]: ends at {format_t(time.time())}")


async def fn_start(run_obj: Runnable):
    print(f"on start callback starts at {format_t(time.time())}")
    await asyncio.sleep(3)
    print(f"on start callback ends at {format_t(time.time())}")


async def fn_end(run_obj: Runnable):
    print(f"on end callback starts at {format_t(time.time())}")
    await asyncio.sleep(2)
    print(f"on end callback ends at {format_t(time.time())}")


runnable = RunnableLambda(test_runnable).with_alisteners(
    on_start=fn_start, on_end=fn_end
)


async def concurrent_runs():
    await asyncio.gather(runnable.ainvoke(2), runnable.ainvoke(3))


asyncio.run(concurrent_runs())
# Result:
# on start callback starts at 2025-03-01T07:05:22.875378+00:00
# on start callback starts at 2025-03-01T07:05:22.875495+00:00
# on start callback ends at 2025-03-01T07:05:25.878862+00:00
# on start callback ends at 2025-03-01T07:05:25.878947+00:00
# Runnable[2s]: starts at 2025-03-01T07:05:25.879392+00:00
# Runnable[3s]: starts at 2025-03-01T07:05:25.879804+00:00
# Runnable[2s]: ends at 2025-03-01T07:05:27.881998+00:00
# on end callback starts at 2025-03-01T07:05:27.882360+00:00
# Runnable[3s]: ends at 2025-03-01T07:05:28.881737+00:00
# on end callback starts at 2025-03-01T07:05:28.882428+00:00
# on end callback ends at 2025-03-01T07:05:29.883893+00:00
# on end callback ends at 2025-03-01T07:05:30.884831+00:00

with_types

with_types(
    *, input_type: type[Input] | None = None, output_type: type[Output] | None = None
) -> Runnable[Input, Output]

Bind input and output types to a Runnable, returning a new Runnable.

PARAMETER	DESCRIPTION
input_type	The input type to bind to the Runnable. TYPE: type[Input] | None DEFAULT: None
output_type	The output type to bind to the Runnable. TYPE: type[Output] | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable with the types bound.

with_retry

with_retry(
    *,
    retry_if_exception_type: tuple[type[BaseException], ...] = (Exception,),
    wait_exponential_jitter: bool = True,
    exponential_jitter_params: ExponentialJitterParams | None = None,
    stop_after_attempt: int = 3,
) -> Runnable[Input, Output]

Create a new Runnable that retries the original Runnable on exceptions.

PARAMETER	DESCRIPTION
retry_if_exception_type	A tuple of exception types to retry on. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
wait_exponential_jitter	Whether to add jitter to the wait time between retries. TYPE: bool DEFAULT: True
stop_after_attempt	The maximum number of attempts to make before giving up. TYPE: int DEFAULT: 3
exponential_jitter_params	Parameters for tenacity.wait_exponential_jitter. Namely: initial, max, exp_base, and jitter (all float values). TYPE: ExponentialJitterParams | None DEFAULT: None

RETURNS	DESCRIPTION
Runnable[Input, Output]	A new Runnable that retries the original Runnable on exceptions.

Example

from langchain_core.runnables import RunnableLambda

count = 0


def _lambda(x: int) -> None:
    global count
    count = count + 1
    if x == 1:
        raise ValueError("x is 1")
    else:
        pass


runnable = RunnableLambda(_lambda)
try:
    runnable.with_retry(
        stop_after_attempt=2,
        retry_if_exception_type=(ValueError,),
    ).invoke(1)
except ValueError:
    pass

assert count == 2

map

map() -> Runnable[list[Input], list[Output]]

Return a new Runnable that maps a list of inputs to a list of outputs.

Calls invoke with each input.

RETURNS	DESCRIPTION
Runnable[list[Input], list[Output]]	A new Runnable that maps a list of inputs to a list of outputs.

Example

from langchain_core.runnables import RunnableLambda


def _lambda(x: int) -> int:
    return x + 1


runnable = RunnableLambda(_lambda)
print(runnable.map().invoke([1, 2, 3]))  # [2, 3, 4]

with_fallbacks

with_fallbacks(
    fallbacks: Sequence[Runnable[Input, Output]],
    *,
    exceptions_to_handle: tuple[type[BaseException], ...] = (Exception,),
    exception_key: str | None = None,
) -> RunnableWithFallbacks[Input, Output]

Add fallbacks to a Runnable, returning a new Runnable.

The new Runnable will try the original Runnable, and then each fallback in order, upon failures.

PARAMETER	DESCRIPTION
fallbacks	A sequence of runnables to try if the original Runnable fails. TYPE: Sequence[Runnable[Input, Output]]
exceptions_to_handle	A tuple of exception types to handle. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
exception_key	If string is specified then handled exceptions will be passed to fallbacks as part of the input under the specified key. If None, exceptions will not be passed to fallbacks. If used, the base Runnable and its fallbacks must accept a dictionary as input. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableWithFallbacks[Input, Output]	A new Runnable that will try the original Runnable, and then each Fallback in order, upon failures.

Example

from typing import Iterator

from langchain_core.runnables import RunnableGenerator


def _generate_immediate_error(input: Iterator) -> Iterator[str]:
    raise ValueError()
    yield ""


def _generate(input: Iterator) -> Iterator[str]:
    yield from "foo bar"


runnable = RunnableGenerator(_generate_immediate_error).with_fallbacks(
    [RunnableGenerator(_generate)]
)
print("".join(runnable.stream({})))  # foo bar

PARAMETER	DESCRIPTION
fallbacks	A sequence of runnables to try if the original Runnable fails. TYPE: Sequence[Runnable[Input, Output]]
exceptions_to_handle	A tuple of exception types to handle. TYPE: tuple[type[BaseException], ...] DEFAULT: (Exception,)
exception_key	If string is specified then handled exceptions will be passed to fallbacks as part of the input under the specified key. If None, exceptions will not be passed to fallbacks. If used, the base Runnable and its fallbacks must accept a dictionary as input. TYPE: str | None DEFAULT: None

RETURNS	DESCRIPTION
RunnableWithFallbacks[Input, Output]	A new Runnable that will try the original Runnable, and then each Fallback in order, upon failures.

as_tool

as_tool(
    args_schema: type[BaseModel] | None = None,
    *,
    name: str | None = None,
    description: str | None = None,
    arg_types: dict[str, type] | None = None,
) -> BaseTool

Create a BaseTool from a Runnable.

as_tool will instantiate a BaseTool with a name, description, and args_schema from a Runnable. Where possible, schemas are inferred from runnable.get_input_schema.

Alternatively (e.g., if the Runnable takes a dict as input and the specific dict keys are not typed), the schema can be specified directly with args_schema.

You can also pass arg_types to just specify the required arguments and their types.

PARAMETER	DESCRIPTION
args_schema	The schema for the tool. TYPE: type[BaseModel] | None DEFAULT: None
name	The name of the tool. TYPE: str | None DEFAULT: None
description	The description of the tool. TYPE: str | None DEFAULT: None
arg_types	A dictionary of argument names to types. TYPE: dict[str, type] | None DEFAULT: None

RETURNS	DESCRIPTION
BaseTool	A BaseTool instance.

Typed dict input:

from typing_extensions import TypedDict
from langchain_core.runnables import RunnableLambda


class Args(TypedDict):
    a: int
    b: list[int]


def f(x: Args) -> str:
    return str(x["a"] * max(x["b"]))


runnable = RunnableLambda(f)
as_tool = runnable.as_tool()
as_tool.invoke({"a": 3, "b": [1, 2]})

dict input, specifying schema via args_schema:

from typing import Any
from pydantic import BaseModel, Field
from langchain_core.runnables import RunnableLambda

def f(x: dict[str, Any]) -> str:
    return str(x["a"] * max(x["b"]))

class FSchema(BaseModel):
    """Apply a function to an integer and list of integers."""

    a: int = Field(..., description="Integer")
    b: list[int] = Field(..., description="List of ints")

runnable = RunnableLambda(f)
as_tool = runnable.as_tool(FSchema)
as_tool.invoke({"a": 3, "b": [1, 2]})

dict input, specifying schema via arg_types:

from typing import Any
from langchain_core.runnables import RunnableLambda


def f(x: dict[str, Any]) -> str:
    return str(x["a"] * max(x["b"]))


runnable = RunnableLambda(f)
as_tool = runnable.as_tool(arg_types={"a": int, "b": list[int]})
as_tool.invoke({"a": 3, "b": [1, 2]})

str input:

from langchain_core.runnables import RunnableLambda


def f(x: str) -> str:
    return x + "a"


def g(x: str) -> str:
    return x + "z"


runnable = RunnableLambda(f) | g
as_tool = runnable.as_tool()
as_tool.invoke("b")

__init__

__init__(**kwargs: Any) -> None

Initialize the tool.

RAISES	DESCRIPTION
TypeError	If args_schema is not a subclass of pydantic BaseModel or dict.

is_lc_serializable classmethod

is_lc_serializable() -> bool

Is this class serializable?

By design, even if a class inherits from Serializable, it is not serializable by default. This is to prevent accidental serialization of objects that should not be serialized.

RETURNS	DESCRIPTION
bool	Whether the class is serializable. Default is False.

get_lc_namespace classmethod

get_lc_namespace() -> list[str]

Get the namespace of the LangChain object.

For example, if the class is langchain.llms.openai.OpenAI, then the namespace is ["langchain", "llms", "openai"]

RETURNS	DESCRIPTION
list[str]	The namespace.

lc_id classmethod

lc_id() -> list[str]

Return a unique identifier for this class for serialization purposes.

The unique identifier is a list of strings that describes the path to the object.

For example, for the class langchain.llms.openai.OpenAI, the id is ["langchain", "llms", "openai", "OpenAI"].

to_json

to_json() -> SerializedConstructor | SerializedNotImplemented

Serialize the Runnable to JSON.

RETURNS	DESCRIPTION
SerializedConstructor | SerializedNotImplemented	A JSON-serializable representation of the Runnable.

to_json_not_implemented

to_json_not_implemented() -> SerializedNotImplemented

Serialize a "not implemented" object.

RETURNS	DESCRIPTION
SerializedNotImplemented	SerializedNotImplemented.

configurable_fields

configurable_fields(
    **kwargs: AnyConfigurableField,
) -> RunnableSerializable[Input, Output]

Configure particular Runnable fields at runtime.

PARAMETER	DESCRIPTION
**kwargs	A dictionary of ConfigurableField instances to configure. TYPE: AnyConfigurableField DEFAULT: {}

RAISES	DESCRIPTION
ValueError	If a configuration key is not found in the Runnable.

RETURNS	DESCRIPTION
RunnableSerializable[Input, Output]	A new Runnable with the fields configured.

from langchain_core.runnables import ConfigurableField
from langchain_openai import ChatOpenAI

model = ChatOpenAI(max_tokens=20).configurable_fields(
    max_tokens=ConfigurableField(
        id="output_token_number",
        name="Max tokens in the output",
        description="The maximum number of tokens in the output",
    )
)

# max_tokens = 20
print("max_tokens_20: ", model.invoke("tell me something about chess").content)

# max_tokens = 200
print(
    "max_tokens_200: ",
    model.with_config(configurable={"output_token_number": 200})
    .invoke("tell me something about chess")
    .content,
)

configurable_alternatives

configurable_alternatives(
    which: ConfigurableField,
    *,
    default_key: str = "default",
    prefix_keys: bool = False,
    **kwargs: Runnable[Input, Output] | Callable[[], Runnable[Input, Output]],
) -> RunnableSerializable[Input, Output]

Configure alternatives for Runnable objects that can be set at runtime.

PARAMETER	DESCRIPTION
which	The ConfigurableField instance that will be used to select the alternative. TYPE: ConfigurableField
default_key	The default key to use if no alternative is selected. TYPE: str DEFAULT: 'default'
prefix_keys	Whether to prefix the keys with the ConfigurableField id. TYPE: bool DEFAULT: False
**kwargs	A dictionary of keys to Runnable instances or callables that return Runnable instances. TYPE: Runnable[Input, Output] | Callable[[], Runnable[Input, Output]] DEFAULT: {}

RETURNS	DESCRIPTION
RunnableSerializable[Input, Output]	A new Runnable with the alternatives configured.

from langchain_anthropic import ChatAnthropic
from langchain_core.runnables.utils import ConfigurableField
from langchain_openai import ChatOpenAI

model = ChatAnthropic(
    model_name="claude-sonnet-4-5-20250929"
).configurable_alternatives(
    ConfigurableField(id="llm"),
    default_key="anthropic",
    openai=ChatOpenAI(),
)

# uses the default model ChatAnthropic
print(model.invoke("which organization created you?").content)

# uses ChatOpenAI
print(
    model.with_config(configurable={"llm": "openai"})
    .invoke("which organization created you?")
    .content
)

__init_subclass__

__init_subclass__(**kwargs: Any) -> None

Validate the tool class definition during subclass creation.

PARAMETER	DESCRIPTION
**kwargs	Additional keyword arguments passed to the parent class. TYPE: Any DEFAULT: {}

RAISES	DESCRIPTION
SchemaAnnotationError	If args_schema has incorrect type annotation.

run

run(
    tool_input: str | dict[str, Any],
    verbose: bool | None = None,
    start_color: str | None = "green",
    color: str | None = "green",
    callbacks: Callbacks = None,
    *,
    tags: list[str] | None = None,
    metadata: dict[str, Any] | None = None,
    run_name: str | None = None,
    run_id: UUID | None = None,
    config: RunnableConfig | None = None,
    tool_call_id: str | None = None,
    **kwargs: Any,
) -> Any

Run the tool.

PARAMETER	DESCRIPTION
tool_input	The input to the tool. TYPE: str | dict[str, Any]
verbose	Whether to log the tool's progress. TYPE: bool | None DEFAULT: None
start_color	The color to use when starting the tool. TYPE: str | None DEFAULT: 'green'
color	The color to use when ending the tool. TYPE: str | None DEFAULT: 'green'
callbacks	Callbacks to be called during tool execution. TYPE: Callbacks DEFAULT: None
tags	Optional list of tags associated with the tool. TYPE: list[str] | None DEFAULT: None
metadata	Optional metadata associated with the tool. TYPE: dict[str, Any] | None DEFAULT: None
run_name	The name of the run. TYPE: str | None DEFAULT: None
run_id	The id of the run. TYPE: UUID | None DEFAULT: None
config	The configuration for the tool. TYPE: RunnableConfig | None DEFAULT: None
tool_call_id	The id of the tool call. TYPE: str | None DEFAULT: None
**kwargs	Keyword arguments to be passed to tool callbacks (event handler) TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Any	The output of the tool.

RAISES	DESCRIPTION
ToolException	If an error occurs during tool execution.

arun async

arun(
    tool_input: str | dict,
    verbose: bool | None = None,
    start_color: str | None = "green",
    color: str | None = "green",
    callbacks: Callbacks = None,
    *,
    tags: list[str] | None = None,
    metadata: dict[str, Any] | None = None,
    run_name: str | None = None,
    run_id: UUID | None = None,
    config: RunnableConfig | None = None,
    tool_call_id: str | None = None,
    **kwargs: Any,
) -> Any

Run the tool asynchronously.

PARAMETER	DESCRIPTION
tool_input	The input to the tool. TYPE: str | dict
verbose	Whether to log the tool's progress. TYPE: bool | None DEFAULT: None
start_color	The color to use when starting the tool. TYPE: str | None DEFAULT: 'green'
color	The color to use when ending the tool. TYPE: str | None DEFAULT: 'green'
callbacks	Callbacks to be called during tool execution. TYPE: Callbacks DEFAULT: None
tags	Optional list of tags associated with the tool. TYPE: list[str] | None DEFAULT: None
metadata	Optional metadata associated with the tool. TYPE: dict[str, Any] | None DEFAULT: None
run_name	The name of the run. TYPE: str | None DEFAULT: None
run_id	The id of the run. TYPE: UUID | None DEFAULT: None
config	The configuration for the tool. TYPE: RunnableConfig | None DEFAULT: None
tool_call_id	The id of the tool call. TYPE: str | None DEFAULT: None
**kwargs	Keyword arguments to be passed to tool callbacks TYPE: Any DEFAULT: {}

RETURNS	DESCRIPTION
Any	The output of the tool.

RAISES	DESCRIPTION
ToolException	If an error occurs during tool execution.

validate_environment classmethod

validate_environment(values: dict) -> Any

Validate the environment.