middleware

[hanzhenbjm]

Privileged issue

• I'm @tiangolo or he asked me directly to create an issue here.

Issue Content

class LogMiddleware(BaseHTTPMiddleware):

    def __init__(self, app):
        super().__init__(app)

    async def dispatch(self, request: Request, call_next) -> Response:
        transaction_id = str(uuid.uuid4()).replace('-', '')
        with logger.contextualize(request_id=transaction_id):
            client = request.client.host
            http_type = request.scope.get("type") + "/" + request.scope.get('http_version')
            header = request.headers.get("user-agent")
            request_url = str(request.url)
            request_time = datetime.datetime.now()
            http_method = request.method
            if http_method == "GET":
                request_content = str(request.query_params)
            elif http_method == "POST":
                body_ = await request.json()
                request_content = str(body_)
        
            response = await call_next(request)
            
            method_code = request.scope.get("route").name if request.scope.get("route") is not None else "",
            if request_url.rfind("docs") != -1:
                return response
            response_time = datetime.datetime.now()
            body = b""
            async for chunk in response.body_iterator:
                body += chunk
            result = json.loads(body.decode("utf-8"))
            response_code = 0 if not isinstance(result, dict) else result.get("code", 0)
  
            logger.bind(
                request_time=request_time.strftime("%Y-%m-%d %H:%M:%S.%f")[:-3],
                response_time=response_time.strftime("%Y-%m-%d %H:%M:%S.%f")[:-3],
                ...
                log_time=datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S.%f")[:-3], ).info("finish")

            return Response(
                content=body,
                status_code=response.status_code,
                headers=dict(response.headers),
                media_type=response.media_type
            )

Are there any problems with writing middleware like this?

            async for chunk in response.body_iterator:
                body += chunk

            body_ = await request.json()

Will this affect performance? Or how to write it more perfectly?

Apart from this, is there any better way to write other codes?
thank you very much!

[killjoy1221]

I think with this sort of middleware, you'll want to use a more low level approach.

class LogMiddleware:
  def __init__(self, app):
    self.app = app

  async def __call__(self, scope, receive, send):
    if scope["type"] != "http":
      await self.app(scope, receive, send)
      return

    with logger.contextualize(...):
      request_time = datetime.datetime.now()
      try:
        await self.app(scope, receive, send)
      finally:
        response_time = datetime.datetime.now()
        logger.bind(...).info("finish")

Let the app handle the response. You only need to worry about the timing. If you want to pass data from the endpoint to the middleware, use the scope. Wrap send and receive if you want to get data from the request or response body.