[BUG] Creating serializer from instance in async context

[lautarodapin]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. ..
2. ..

class Message(models.Model):
    text = models.TextField()
    user = models.ForeignKey(User, related_name="messages", on_delete=modelsCASCADE)

class MyConsumer(GenericAsyncAPIConsumer):
    queryset = Message.objects.all()
    serializer_class = MessageSerializer
    chat_room_name : Optional[str]

    @action()
    async def join_chat(self, chat: int, **kwargs):
        self.chat_room_name = f"chat_{chat}"
        await self.channel_layer.group_add(
            self.chat_room_name,
            self.channel_name,
        )
        user_serializer = await database_sync_to_async(UserSerializer)(self.scope["user"], many=False)
        await self.channel_layer.group_send(
            self.chat_room_name,
            {
                "type": "notification",
                "message": f"{self.scope['user'].username} joined the chat",
                "user": user_serializer.data,
                "chat": chat
            }
        )
    async def notification(self, event):
        content = dict(
            action="notification",
            message=event["message"],
            chat=event["chat"],
            user=event["user"],
            status=status.HTTP_200_OK
        )
        await self.send_json(content)

    

When I send the action to the websocket, it should add to a group of users, and send to each one the notification, with the key user that is the user that executes the action. BUT when i want to create the serializer in the async context, it never ends.

LOG

      # Test join chat.
        await communicator.send_json_to({
            "action": "join_chat",
            "chat": chat.pk,
            "request_id": now().timestamp(),
        })
>       response = await communicator.receive_json_from()

backend\tests\test_channels_rest_consumers.py:103:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
venv\lib\site-packages\channels\testing\websocket.py:93: in receive_json_from
    payload = await self.receive_from(timeout)
venv\lib\site-packages\channels\testing\websocket.py:72: in receive_from
    response = await self.receive_output(timeout)
venv\lib\site-packages\asgiref\testing.py:78: in receive_output
    self.future.result()
venv\lib\site-packages\channels\routing.py:150: in __call__
    return await application(
venv\lib\site-packages\channels\consumer.py:94: in app
    return await consumer(scope, receive, send)
venv\lib\site-packages\channels\consumer.py:58: in __call__
    await await_many_dispatch(
venv\lib\site-packages\channels\utils.py:51: in await_many_dispatch
    await dispatch(result)
venv\lib\site-packages\channels\consumer.py:73: in dispatch
    await handler(message)
venv\lib\site-packages\channels\generic\websocket.py:196: in websocket_receive
    await self.receive(text_data=message["text"])
venv\lib\site-packages\channels\generic\websocket.py:259: in receive
    await self.receive_json(await self.decode_json(text_data), **kwargs)
venv\lib\site-packages\djangochannelsrestframework\consumers.py:160: in receive_json
    await self.handle_action(action, request_id=request_id, **content)
venv\lib\site-packages\djangochannelsrestframework\consumers.py:151: in handle_action
    await self.handle_exception(exc, action=action, request_id=request_id)
venv\lib\site-packages\djangochannelsrestframework\consumers.py:117: in handle_exception
    raise exc
venv\lib\site-packages\djangochannelsrestframework\consumers.py:144: in handle_action
    response = await method(request_id=request_id, action=action, **kwargs)
backend\consumers.py:52: in join_chat
    "user": user_serializer.data,
venv\lib\site-packages\rest_framework\serializers.py:548: in data
    ret = super().data
venv\lib\site-packages\rest_framework\serializers.py:246: in data
    self._data = self.to_representation(self.instance)
venv\lib\site-packages\rest_framework\serializers.py:515: in to_representation
    ret[field.field_name] = field.to_representation(attribute)
venv\lib\site-packages\rest_framework\serializers.py:663: in to_representation
    return [
venv\lib\site-packages\django\db\models\query.py:280: in __iter__
    self._fetch_all()
venv\lib\site-packages\django\db\models\query.py:1324: in _fetch_all
    self._result_cache = list(self._iterable_class(self))
venv\lib\site-packages\django\db\models\query.py:51: in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
venv\lib\site-packages\django\db\models\sql\compiler.py:1167: in execute_sql
    cursor = self.connection.cursor()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  

args = (<django.db.backends.sqlite3.base.DatabaseWrapper object at 0x0000011228A21400>,), kwargs = {}, event_loop = <_WindowsSelectorEventLoop running=False closed=False debug=False>

    @functools.wraps(func)
    def inner(*args, **kwargs):
        if not os.environ.get('DJANGO_ALLOW_ASYNC_UNSAFE'):
            # Detect a running event loop in this thread.
            try:
                event_loop = asyncio.get_event_loop()
            except RuntimeError:
                pass
            else:
                if event_loop.is_running():
>                   raise SynchronousOnlyOperation(message)
E                   django.core.exceptions.SynchronousOnlyOperation: You cannot call this from an async context - use a thread or sync_to_async.

venv\lib\site-packages\django\utils\asyncio.py:24: SynchronousOnlyOperation

• OS: Windows 10

[hishnash]

DRF does the DB query when you do user_serializer.data not on its __init__ method... the cleanest way to deal with this is to create a method that creates the UserSerializer and returns the .data.

[lautarodapin]

DRF does the DB query when you do user_serializer.data not on its __init__ method... the cleanest way to deal with this is to create a method that creates the UserSerializer and returns the .data.

Ok thanks! Will try it

[hishnash]

@lautarodapin did this work for you?

[lautarodapin]

@lautarodapin did this work for you?

yes thanks! the easiest way was to decorate a method for serializing the current user

@database_sync_to_async
def current_user(self) -> ReturnDict:
  return UserSerializer(self.scope["user"], many=False).data

[lautarodapin]

@hishnash do you have a chat or some other active contact app like slack?

I just realized that this isnt a query search xD

 @chats_messages_handler.groups_for_signal
  def chats_messages_handler(self, instance: Message, **kwargs):
      # this block of code is called very often *DO NOT make DB QUERIES HERE*
      yield f'-chat___________{instance.chat_id}'

  @chats_messages_handler.groups_for_consumer
  def chats_messages_handler(self, chat: int, **kwargs):
      # This is called when you subscribe/unsubscribe
      if chat is not None:
          yield f'-chat___________{chat}'

[hishnash]

@lautarodapin you can DM me on twitter https://twitter.com/hishnash