From 6ada2d0fe805a053b977bbc152ed84df64f80161 Mon Sep 17 00:00:00 2001
From: Phil Freeman <paf31@cantab.net>
Date: Mon, 30 Dec 2019 10:45:38 -0800
Subject: [PATCH 1/2] Report errors in parallel when batching

---
 server/src-lib/Hasura/GraphQL/Transport/HTTP.hs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/server/src-lib/Hasura/GraphQL/Transport/HTTP.hs b/server/src-lib/Hasura/GraphQL/Transport/HTTP.hs
index 19f1b63a47628..d72b12d4b4fd3 100644
--- a/server/src-lib/Hasura/GraphQL/Transport/HTTP.hs
+++ b/server/src-lib/Hasura/GraphQL/Transport/HTTP.hs
@@ -55,8 +55,13 @@ runGQBatched reqId userInfo reqHdrs reqs =
       -- It's unclear what we should do if we receive multiple
       -- responses with distinct headers, so just do the simplest thing
       -- in this case, and don't forward any.
-      let removeHeaders = flip HttpResponse Nothing . encJFromList . map _hrBody
-      removeHeaders <$> traverse (runGQ reqId userInfo reqHdrs) batch
+      let removeHeaders = 
+            flip HttpResponse Nothing 
+            . encJFromList 
+            . map (either (encJFromJValue . encodeGQErr False) _hrBody)
+          try = flip catchError (pure . Left) . fmap Right
+      fmap removeHeaders $ 
+        traverse (try . runGQ reqId userInfo reqHdrs) batch
 
 runHasuraGQ
   :: ( MonadIO m

From 25d883d68d23dcfe2227ec5a09fcd993e5b3026a Mon Sep 17 00:00:00 2001
From: Phil Freeman <paf31@cantab.net>
Date: Mon, 30 Dec 2019 11:58:28 -0800
Subject: [PATCH 2/2] Add some more test cases

---
 .../select_query_batching_with_mutation.yaml  | 42 +++++++++++++++++++
 .../select_query_batching_with_one_error.yaml | 26 ++++++++++++
 server/tests-py/test_graphql_queries.py       |  8 ++++
 3 files changed, 76 insertions(+)
 create mode 100644 server/tests-py/queries/graphql_query/basic/select_query_batching_with_mutation.yaml
 create mode 100644 server/tests-py/queries/graphql_query/basic/select_query_batching_with_one_error.yaml

diff --git a/server/tests-py/queries/graphql_query/basic/select_query_batching_with_mutation.yaml b/server/tests-py/queries/graphql_query/basic/select_query_batching_with_mutation.yaml
new file mode 100644
index 0000000000000..c18cfc68e09ed
--- /dev/null
+++ b/server/tests-py/queries/graphql_query/basic/select_query_batching_with_mutation.yaml
@@ -0,0 +1,42 @@
+description: GraphQL query to test batching with mixed queries and mutations
+url: /v1/graphql
+status: 200
+response:
+  - data:
+      update_user:
+        affected_rows: 1
+        returning:
+        - id: '2'
+  - data:
+      user:
+      - id: '1'
+        name: User 1
+      - id: '2'
+        name: Temp User
+  - data:
+      update_user:
+        affected_rows: 1
+        returning:
+        - id: '2'
+query:
+  - query: |
+      mutation {
+        update_user(where: {number: {_eq: "123456780"}}, _set: {name: "Temp User"}) {
+          affected_rows
+          returning { id }
+        }
+      }
+  - query: |
+      query {
+        user {
+          id
+          name
+        }
+      }
+  - query: |
+      mutation {
+        update_user(where: {number: {_eq: "123456780"}}, _set: {name: "User 2"}) {
+          affected_rows
+          returning { id }
+        }
+      }
diff --git a/server/tests-py/queries/graphql_query/basic/select_query_batching_with_one_error.yaml b/server/tests-py/queries/graphql_query/basic/select_query_batching_with_one_error.yaml
new file mode 100644
index 0000000000000..7b956a61cd619
--- /dev/null
+++ b/server/tests-py/queries/graphql_query/basic/select_query_batching_with_one_error.yaml
@@ -0,0 +1,26 @@
+description: GraphQL query to test error reporting when batching requests
+url: /v1/graphql
+status: 200
+response:
+  - errors:
+    - extensions:
+        path: $.selectionSet.does_not_exist
+        code: validation-failed
+      message: "field \"does_not_exist\" not found in type: 'query_root'"
+  - data:
+      author:
+      - id: 1
+      - id: 2
+query:
+  - query: |
+      query {
+        does_not_exist {
+          id
+        }
+      }
+  - query: |
+      query {
+        author {
+          id
+        }
+      }
diff --git a/server/tests-py/test_graphql_queries.py b/server/tests-py/test_graphql_queries.py
index 9e2df8bdf4924..4300b67261e21 100644
--- a/server/tests-py/test_graphql_queries.py
+++ b/server/tests-py/test_graphql_queries.py
@@ -64,6 +64,14 @@ def test_select_query_batching(self, hge_ctx, transport):
         transport = 'http'
         check_query_f(hge_ctx, self.dir() + "/select_query_batching.yaml", transport)
 
+    def test_select_query_batching_with_mutation(self, hge_ctx, transport):
+        transport = 'http'
+        check_query_f(hge_ctx, self.dir() + "/select_query_batching_with_mutation.yaml", transport)
+
+    def test_select_query_batching_with_one_error(self, hge_ctx, transport):
+        transport = 'http'
+        check_query_f(hge_ctx, self.dir() + "/select_query_batching_with_one_error.yaml", transport)
+
     @classmethod
     def dir(cls):
         return 'queries/graphql_query/basic'