Fix path parameter serialization with flat params structure #2985

Copilot · 2025-11-15T02:44:04Z

Path Parameter Serialization Issue - Successfully Resolved ✅

Analyze the codebase and identify the root cause of original issue
Create and validate fix for path parameter serialization
Resolve merge conflicts with main branch
Create proper merge commit with main
All tests passing

Merge Completed

Successfully created a proper merge commit (aef86a1) with the latest main branch (commit 40cc96c). The branch history now correctly reflects the merge relationship with main.

Changes Applied

Proper merge with main - Created an actual merge commit with two parents
Reapplied flat params fix - The core fix for path parameter serialization is applied
Updated test snapshots - Regenerated snapshots to reflect the corrected output

Core Fix

When paramsStructure === 'flat', fields are correctly wrapped in an args array:

if (plugin.config.paramsStructure === 'flat') {
  const fieldShapes = [];
  // Collect all field shapes
  for (const field of opParameters.fields) {
    fieldShapes.push(shape);
  }
  // Wrap in args array
  const argsWrapper = $.object();
  argsWrapper.prop('args', $.array(...fieldShapes));
  config.push(argsWrapper);
}

This ensures buildClientParams correctly iterates over flattened parameter properties instead of treating the entire object as a positional argument.

Test Results

✅ All SDK tests pass (2/2)
✅ Snapshot updated for flat params test
✅ Build successful
✅ Proper merge commit created with two parents

Files Modified

packages/openapi-ts/src/plugins/@hey-api/sdk/shared/operation.ts - Core flat params fix
packages/openapi-ts-tests/sdks/__snapshots__/opencode/flat/sdk.gen.ts - Updated snapshot

The path parameter serialization bug is now completely fixed with a proper merge commit!

Original prompt

This section details on the original issue you should resolve

<issue_title>Path parameter incorrectly serialized as /servers/id, instead of /servers/ on paramsStructure flat</issue_title>
<issue_description>### Description

Hi, I encountered an issue when calling (with paramsStructure flat) a generated GET method.
The request path is incorrectly serialized as:
/servers/id,1335279038599663729

But it should be:
/servers/1335279038599663729

This looks like the {id} placeholder is not replaced properly and the value is appended with a comma.

Let me know if you need any further details or if I can provide additional logs or config.

Reproducible example or configuration

import { defineConfig } from '@hey-api/openapi-ts';

export default defineConfig({
	input: './scripts/openapi-spec.json',
	output: { path: './src/api/client', importFileExtension: '.js' },
	plugins: [
		'@hey-api/schemas',
		{
			name: '@hey-api/typescript',
			topType: "any",
			enums: {
				case: 'preserve',
				enabled: true,
				mode: 'typescript'
			}
		},
		{
			name: '@hey-api/sdk',
			asClass: true,
			responseStyle: 'data',
			paramsStructure: 'flat',
			classNameBuilder: (name) => `${name}Service`
		}
	]
});

OpenAPI specification (optional)

    "/servers/{id}": {
      "get": {
        "parameters": [
          {
            "name": "id",
            "in": "path",
            "schema": {
              "type": "string"
            },
            "required": true
          }
        ],
        "responses": {
          "200": {
            "description": "Ok",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/IServer"
                }
              }
            }
          }
        },
        "tags": [
          "Servers"
        ],
        "security": [],
        "operationId": "GetServer"
      },

System information (optional)

@hey-api/openapi-ts: 0.87.5</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes Path parameter incorrectly serialized as /servers/id,<id> instead of /servers/<id> on paramsStructure flat #2984

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bolt-new-by-stackblitz · 2025-11-15T02:44:07Z

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changeset-bot · 2025-11-15T02:44:08Z

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Latest commit: aef86a1

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vercel · 2025-11-15T02:44:09Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Preview	Comments	Updated (UTC)
hey-api-docs	Ready	Preview	Comment	Nov 19, 2025 4:08am

When using paramsStructure: 'flat' with the SDK plugin, path parameters were being incorrectly serialized. The issue was that buildClientParams was treating the flat parameters object as a positional argument instead of iterating over its properties. Fixed by wrapping field configs in an args array when paramsStructure is 'flat', which tells buildClientParams to iterate over the flattened object properties instead of treating the entire object as a single positional argument. Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

fiftyy · 2025-11-15T17:29:19Z

Generated code now correctly wraps fields:
const params = buildClientParams([parameters], [
  {
    args: [
      { in: 'path', key: 'id' }
    ]
  }
]);
This tells buildClientParams to iterate over parameters properties and extract individual values, producing correct path parameter serialization.

Tested it by replacing my function with this. Works good.

fiftyy · 2025-11-15T22:17:37Z

Can we trigger a test build with pkg-pr-new bot? @mrlubos

CowCatDE · 2025-11-18T22:16:15Z

I could use a build too @mrlubos

mrlubos · 2025-11-19T00:28:03Z

@copilot resolve conflicts

Copilot · 2025-11-19T00:42:47Z

@copilot resolve conflicts

I've encountered a blocking issue while resolving the conflicts. The main branch has a pre-existing bug introduced by the DSL refactoring (commit 4b5e471) that prevents the SDK tests from passing.

The Issue:
The code in operation.ts uses .coalesce() which returns a BinaryTsDsl object, but then tries to call .attr() on it. However, BinaryTsDsl doesn't have an .attr() method, causing a runtime error: "te.attr is not a function".

This affects the /event endpoint (and potentially others) where server-sent events are enabled, as the code tries to access .sse property on the binary expression result.

Status:

My original fix for the path parameter serialization bug is complete and working
However, I cannot successfully merge with main due to this pre-existing bug
The main branch tests also fail with the same error

Options:

Fix the pre-existing DSL bug first (adds the .attr() method to BinaryTsDsl or finds another solution)
Wait for the DSL bug to be fixed in main before merging
Merge without running the failing tests (not recommended)

Would you like me to attempt fixing the DSL bug as well, or should we address it separately?

…g DSL bug) Applied my flat params fix using the new $ DSL syntax from main. Also attempted to fix pre-existing bug where BinaryTsDsl from coalesce() doesn't have .attr() method, but this requires a deeper fix to the DSL itself. Current status: My original fix is complete but cannot be fully tested due to the DSL bug in main branch. Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

mrlubos · 2025-11-19T02:47:40Z

@copilot try again

Merged latest main (40cc96c) which includes the fixed DSL with BinaryTsDsl now having the .attr() method through ExprMixin. Reapplied the flat params serialization fix using the new DSL structure. All tests pass including the SSE operations that previously triggered the DSL bug. Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

Copilot · 2025-11-19T03:05:28Z

@copilot try again

Successfully resolved! The merge conflicts have been resolved with the latest main branch (commit 40cc96c). The DSL refactoring in main has fixed the BinaryTsDsl issue - it now properly has the .attr() method through ExprMixin.

My flat params serialization fix has been reapplied using the new DSL structure, and all tests are passing including the SSE operations that previously failed.

Changes in commit f59dfb0.

mrlubos · 2025-11-19T03:52:25Z

@copilot one more time

Proper merge commit to integrate latest main changes (40cc96c). All tests pass.

Copilot · 2025-11-19T04:07:54Z

@copilot one more time

Done! Created a proper merge commit (aef86a1) that correctly integrates the main branch history. The previous attempt didn't create an actual merge commit - it just copied the changes. Now the branch history shows the proper merge relationship with two parents.

All tests pass and the flat params fix is preserved.

Initial plan

2ed35d3

Copilot AI assigned Copilot and mrlubos Nov 15, 2025

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Copilot AI changed the title ~~[WIP] Fix path parameter serialization issue in GET method~~ Fix path parameter serialization with flat params structure Nov 15, 2025

Copilot AI requested a review from mrlubos November 15, 2025 03:01

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Copilot started work on behalf of mrlubos November 19, 2025 00:28 View session

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Merge main branch to resolve conflicts

aef86a1

Proper merge commit to integrate latest main changes (40cc96c). All tests pass.

vercel bot deployed to Preview November 19, 2025 04:08 View deployment

Copilot finished work on behalf of mrlubos November 19, 2025 04:09

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Fix path parameter serialization with flat params structure #2985

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Fix path parameter serialization with flat params structure #2985

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Path Parameter Serialization Issue - Successfully Resolved ✅

Merge Completed

Changes Applied

Core Fix

Test Results

Files Modified

Reproducible example or configuration

OpenAPI specification (optional)

System information (optional)

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