Allow "extensions" field in remote schema response

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2818
GitOrigin-RevId: 505e8bae6d3e11199c229bd2b86af09161eb8b66

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Next release
 (Add highlights/major features below)
 - server: log locking DB queries during source catalog migration
+- server: fix to allow remote schema response to contain an "extensions" field (#7143)
 - console: add comments to tracked functions
 
 ### Bug fixes and improvements

server/src-lib/Hasura/GraphQL/Transport/HTTP.hs

@@ -545,6 +545,21 @@ coalescePostgresMutations plan = do
     _ -> Nothing
   Just (oneSourceConfig, mutations)
 
+data GraphQLResponse
+  = GraphQLResponseErrors [J.Value]
+  | GraphQLResponseData JO.Value
+
+decodeGraphQLResponse :: LBS.ByteString -> Either Text GraphQLResponse
+decodeGraphQLResponse bs = do
+  val <- mapLeft T.pack $ JO.eitherDecode bs
+  valObj <- JO.asObject val
+  case JO.lookup "errors" valObj of
+    Just (JO.Array errs) -> Right $ GraphQLResponseErrors (toList $ JO.fromOrdered <$> errs)
+    Just _ -> Left "Invalid \"errors\" field in response from remote"
+    Nothing -> do
+      dataVal <- JO.lookup "data" valObj `onNothing` Left "Missing \"data\" field in response from remote"
+      Right $ GraphQLResponseData dataVal
+
 extractFieldFromResponse ::
   forall m.
   Monad m =>
@@ -557,14 +572,13 @@ extractFieldFromResponse fieldName rsi resultCustomizer resp = do
   let namespace = fmap G.unName $ _rscNamespaceFieldName $ rsCustomizer rsi
       fieldName' = G.unName $ _rfaAlias fieldName
   -- TODO: use RootFieldAlias for remote fields
-  val <- onLeft (JO.eitherDecode resp) $ do400 . T.pack
-  valObj <- onLeft (JO.asObject val) do400
   dataVal <-
-    applyResultCustomizer resultCustomizer <$> case JO.toList valObj of
-      [("data", v)] -> pure v
-      _ -> case JO.lookup "errors" valObj of
-        Just (JO.Array err) -> doGQExecError $ toList $ fmap JO.fromOrdered err
-        _ -> do400 "Received invalid JSON value from remote"
+    applyResultCustomizer resultCustomizer
+      <$> do
+        graphQLResponse <- decodeGraphQLResponse resp `onLeft` do400
+        case graphQLResponse of
+          GraphQLResponseErrors errs -> doGQExecError errs
+          GraphQLResponseData d -> pure d
   case namespace of
     Just _ ->
       -- If using a custom namespace field then the response from the remote server

server/tests-py/graphql_server.py

@@ -12,8 +12,8 @@ from graphql import GraphQLError
 
 HGE_URLS=[]
 
-def mkJSONResp(graphql_result):
-    return Response(HTTPStatus.OK, graphql_result.to_dict(),
+def mkJSONResp(graphql_result, extensions={}):
+    return Response(HTTPStatus.OK, {**graphql_result.to_dict(), **extensions},
                     {'Content-Type': 'application/json'})
 
 
@@ -48,6 +48,17 @@ class HelloGraphQL(RequestHandler):
         res = hello_schema.execute(request.json['query'])
         return mkJSONResp(res)
 
+class HelloGraphQLExtensions(RequestHandler):
+    def get(self, request):
+        return Response(HTTPStatus.METHOD_NOT_ALLOWED)
+
+    def post(self, request):
+        if not request.json:
+            return Response(HTTPStatus.BAD_REQUEST)
+        res = hello_schema.execute(request.json['query'])
+        extensions = {'extensions': {'message': 'an extra field in response object'}}
+        return mkJSONResp(res, extensions)
+
 class User(graphene.ObjectType):
     id = graphene.Int()
     username = graphene.String()
@@ -785,6 +796,7 @@ class MessagesGraphQL(RequestHandler):
 handlers = MkHandlers({
     '/hello': HelloWorldHandler,
     '/hello-graphql': HelloGraphQL,
+    '/hello-graphql-extensions': HelloGraphQLExtensions,
     '/user-graphql': UserGraphQL,
     '/country-graphql': CountryGraphQL,
     '/character-iface-graphql' : CharacterInterfaceGraphQL,

server/tests-py/test_schema_stitching.py

@@ -297,6 +297,28 @@ class TestRemoteSchemaBasic:
         st_code, resp = hge_ctx.v1q_f(self.dir + '/basic_bulk_remove_add.yaml')
         assert st_code == 200, resp
 
+class TestRemoteSchemaBasicExtensions:
+    """ basic => no hasura tables are tracked """
+
+    teardown = {"type": "clear_metadata", "args": {}}
+    dir = 'queries/remote_schemas'
+
+    @pytest.fixture(autouse=True)
+    def transact(self, request, hge_ctx):
+        config = request.config
+        # This is needed for supporting server upgrade tests
+        # Some marked tests in this class will be run as server upgrade tests
+        if not config.getoption('--skip-schema-setup'):
+            q = mk_add_remote_q('simple 1', 'http://localhost:5000/hello-graphql-extensions')
+            st_code, resp = hge_ctx.v1q(q)
+            assert st_code == 200, resp
+        yield
+        if request.session.testsfailed > 0 or not config.getoption('--skip-schema-teardown'):
+            hge_ctx.v1q(self.teardown)
+
+    def test_remote_query(self, hge_ctx):
+        check_query_f(hge_ctx, self.dir + '/basic_query.yaml')
+
 
 class TestAddRemoteSchemaTbls:
     """ tests with adding a table in hasura """