🔨 refactoring in fastapi/routing

fastapi/routing.py

@@ -380,7 +380,6 @@ def get_request_handler(
         actual_strict_content_type = strict_content_type
 
     async def app(request: Request) -> Response:
-        response: Response | None = None
         file_stack = request.scope.get("fastapi_middleware_astack")
         assert isinstance(file_stack, AsyncExitStack), (
             "fastapi_middleware_astack not found in request scope"
@@ -449,7 +448,6 @@ def get_request_handler(
             raise http_error from e
 
         # Solve dependencies and run path operation function, auto-closing dependencies
-        errors: list[Any] = []
         async_exit_stack = request.scope.get("fastapi_inner_astack")
         assert isinstance(async_exit_stack, AsyncExitStack), (
             "fastapi_inner_astack not found in request scope"
@@ -464,15 +462,17 @@ def get_request_handler(
         )
         errors = solved_result.errors
         assert dependant.call  # For types
-        if not errors:
+        if errors:
+            raise RequestValidationError(
+                errors, body=body, endpoint_ctx=endpoint_ctx
+            )
+
         # Shared serializer for stream items (JSONL and SSE).
         # Validates against stream_item_field when set, then
         # serializes to JSON bytes.
         def _serialize_data(data: Any) -> bytes:
             if stream_item_field:
-                    value, errors_ = stream_item_field.validate(
-                        data, {}, loc=("response",)
-                    )
+                value, errors_ = stream_item_field.validate(data, {}, loc=("response",))
                 if errors_:
                     ctx = endpoint_ctx or EndpointContext()
                     raise ResponseValidationError(
@@ -489,7 +489,7 @@ def get_request_handler(
                     exclude_defaults=response_model_exclude_defaults,
                     exclude_none=response_model_exclude_none,
                 )
-                else:
+
             data = jsonable_encoder(data)
             return json.dumps(data).encode("utf-8")
 
@@ -519,9 +519,7 @@ def get_request_handler(
                         retry=item.retry,
                         comment=item.comment,
                     )
-                    else:
-                        # Plain object: validate + serialize via
-                        # stream_item_field (if set) and wrap in data field
+
                 return format_sse_event(
                     data_str=_serialize_data(item).decode("utf-8")
                 )
@@ -583,15 +581,9 @@ def get_request_handler(
                     yield receive_keepalive
                     tg.cancel_scope.cancel()
 
-                # Enter the SSE context manager on the request-scoped
-                # exit stack. The stack outlives the streaming response,
-                # so __aexit__ runs via proper structured teardown, not
-                # via GeneratorExit thrown into an async generator.
             sse_receive_stream = await async_exit_stack.enter_async_context(
                 _sse_producer_cm()
             )
-                # Ensure the receive stream is closed when the exit stack
-                # unwinds, preventing ResourceWarning from __del__.
             async_exit_stack.push_async_callback(sse_receive_stream.aclose)
 
             async def _sse_with_checkpoints(
@@ -607,7 +599,6 @@ def get_request_handler(
             sse_stream_content: AsyncIterator[bytes] | Iterator[bytes] = (
                 _sse_with_checkpoints(sse_receive_stream)
             )
-
             response = StreamingResponse(
                 sse_stream_content,
                 media_type="text/event-stream",
@@ -617,7 +608,9 @@ def get_request_handler(
             # For Nginx proxies to not buffer server sent events
             response.headers["X-Accel-Buffering"] = "no"
             response.headers.raw.extend(solved_result.response.headers.raw)
-            elif is_json_stream:
+            return response
+
+        if is_json_stream:
             # Generator endpoint: stream as JSONL
             gen = dependant.call(**solved_result.values)
 
@@ -650,8 +643,10 @@ def get_request_handler(
                 background=solved_result.background_tasks,
             )
             response.headers.raw.extend(solved_result.response.headers.raw)
-            elif dependant.is_async_gen_callable or dependant.is_gen_callable:
-                # Raw streaming with explicit response_class (e.g. StreamingResponse)
+            return response
+
+        if dependant.is_async_gen_callable or dependant.is_gen_callable:
+            # Raw streaming with explicit response_class
             gen = dependant.call(**solved_result.values)
             if dependant.is_async_gen_callable:
 
@@ -670,7 +665,8 @@ def get_request_handler(
             )
             response = actual_response_class(content=gen, **response_args)
             response.headers.raw.extend(solved_result.response.headers.raw)
-            else:
+            return response
+
         raw_response = await run_endpoint_function(
             dependant=dependant,
             values=solved_result.values,
@@ -679,8 +675,8 @@ def get_request_handler(
         if isinstance(raw_response, Response):
             if raw_response.background is None:
                 raw_response.background = solved_result.background_tasks
-                    response = raw_response
-                else:
+            return raw_response
+
         response_args = _build_response_args(
             status_code=status_code, solved_result=solved_result
         )
@@ -716,14 +712,6 @@ def get_request_handler(
         if not is_body_allowed_for_status_code(response.status_code):
             response.body = b""
         response.headers.raw.extend(solved_result.response.headers.raw)
-        if errors:
-            validation_error = RequestValidationError(
-                errors, body=body, endpoint_ctx=endpoint_ctx
-            )
-            raise validation_error
-
-        # Return response
-        assert response
         return response
 
     return app