feat(event_handlers) Add support for returning dict, status-code tuples from resolvers (#1853)

Co-authored-by: Matthew Coyle <[email protected]>
Co-authored-by: Rúben Fonseca <[email protected]>

Author: 3 people

aws_lambda_powertools/event_handler/api_gateway.py

@@ -728,21 +728,26 @@ def _call_exception_handler(self, exp: Exception, route: Route) -> Optional[Resp
 
         return None
 
-    def _to_response(self, result: Union[Dict, Response]) -> Response:
+    def _to_response(self, result: Union[Dict, Tuple, Response]) -> Response:
         """Convert the route's result to a Response
 
-         2 main result types are supported:
+         3 main result types are supported:
 
         - Dict[str, Any]: Rest api response with just the Dict to json stringify and content-type is set to
           application/json
+        - Tuple[dict, int]: Same dict handling as above but with the option of including a status code
         - Response: returned as is, and allows for more flexibility
         """
+        status_code = HTTPStatus.OK
         if isinstance(result, Response):
             return result
+        elif isinstance(result, tuple) and len(result) == 2:
+            # Unpack result dict and status code from tuple
+            result, status_code = result
 
         logger.debug("Simple response detected, serializing return before constructing final response")
         return Response(
-            status_code=200,
+            status_code=status_code,
             content_type=content_types.APPLICATION_JSON,
             body=self._json_dump(result),
         )

docs/core/event_handler/api_gateway.md

@@ -45,7 +45,12 @@ A resolver will handle request resolution, including [one or more routers](#spli
 For resolvers, we provide: `APIGatewayRestResolver`, `APIGatewayHttpResolver`, `ALBResolver`, and `LambdaFunctionUrlResolver`. From here on, we will default to `APIGatewayRestResolver` across examples.
 
 ???+ info "Auto-serialization"
-    We serialize `Dict` responses as JSON, trim whitespace for compact responses, and set content-type to `application/json`.
+    We serialize `Dict` responses as JSON, trim whitespace for compact responses, set content-type to `application/json`, and
+    return a 200 OK HTTP status. You can optionally set a different HTTP status code as the second argument of the tuple:
+
+    ```python hl_lines="15 16"
+    --8<-- "examples/event_handler_rest/src/getting_started_return_tuple.py"
+    ```
 
 #### API Gateway REST API
 

examples/event_handler_rest/src/getting_started_return_tuple.py

@@ -0,0 +1,20 @@
+import requests
+from requests import Response
+
+from aws_lambda_powertools.event_handler import ALBResolver
+from aws_lambda_powertools.utilities.typing import LambdaContext
+
+app = ALBResolver()
+
+
+@app.post("/todo")
+def create_todo():
+    data: dict = app.current_event.json_body
+    todo: Response = requests.post("https://jsonplaceholder.typicode.com/todos", data=data)
+
+    # Returns the created todo object, with a HTTP 201 Created status
+    return {"todo": todo.json()}, 201
+
+
+def lambda_handler(event: dict, context: LambdaContext) -> dict:
+    return app.resolve(event, context)

tests/functional/event_handler/test_api_gateway.py

@@ -1579,3 +1579,39 @@ def get_lambda() -> Response:
     # AND set the current_event type as APIGatewayProxyEvent
     assert result["statusCode"] == 200
     assert result2["statusCode"] == 200
+
+
+def test_dict_response():
+    # GIVEN a dict is returned
+    app = ApiGatewayResolver()
+
+    @app.get("/lambda")
+    def get_message():
+        return {"message": "success"}
+
+    # WHEN calling handler
+    response = app({"httpMethod": "GET", "path": "/lambda"}, None)
+
+    # THEN the body is correctly formatted, the status code is 200 and the content type is json
+    assert response["statusCode"] == 200
+    assert response["multiValueHeaders"]["Content-Type"] == [content_types.APPLICATION_JSON]
+    response_body = json.loads(response["body"])
+    assert response_body["message"] == "success"
+
+
+def test_dict_response_with_status_code():
+    # GIVEN a dict is returned with a status code
+    app = ApiGatewayResolver()
+
+    @app.get("/lambda")
+    def get_message():
+        return {"message": "success"}, 201
+
+    # WHEN calling handler
+    response = app({"httpMethod": "GET", "path": "/lambda"}, None)
+
+    # THEN the body is correctly formatted, the status code is 201 and the content type is json
+    assert response["statusCode"] == 201
+    assert response["multiValueHeaders"]["Content-Type"] == [content_types.APPLICATION_JSON]
+    response_body = json.loads(response["body"])
+    assert response_body["message"] == "success"