AttributeError: 'NoneType' object has no attribute 'group_add'

[Quvonchbek Bobojonov]

I'm learning Django Chanel

import json
from asgiref.sync import async_to_sync
from channels.generic.websocket import WebsocketConsumer


class ChatConsumer(WebsocketConsumer):
    def connect(self):
        self.room_name = self.scope['url_route']['kwargs']['room_name']
        self.room_group_name = 'chat_%s' % self.room_name

        # Join room group
        async_to_sync(self.channel_layer.group_add)(
            self.room_group_name,
            self.channel_name
        )

        self.accept()

    def disconnect(self, close_code):
        # Leave room group
        async_to_sync(self.channel_layer.group_discard)(
            self.room_group_name,
            self.channel_name
        )

    # Receive message from WebSocket
    def receive(self, text_data):
        text_data_json = json.loads(text_data)
        message = text_data_json['message']

        # Send message to room group
        async_to_sync(self.channel_layer.group_send)(
            self.room_group_name,
            {
                'type': 'chat_message',
                'message': message
            }
        )

    # Receive message from room group
    def chat_message(self, event):
        message = event['message']

        # Send message to WebSocket
        self.send(text_data=json.dumps({
            'message': message
        }))

and

# chat/consumers.py
import json

from channels.generic.websocket import AsyncWebsocketConsumer


class ChatConsumer(AsyncWebsocketConsumer):
    async def connect(self):
        self.room_name = self.scope["url_route"]["kwargs"]["room_name"]
        self.room_group_name = f"chat_{self.room_name}"

        # Join room group
        await self.channel_layer.group_add(self.room_group_name, self.channel_name)

        await self.accept()

    async def disconnect(self, close_code):
        # Leave room group
        await self.channel_layer.group_discard(self.room_group_name, self.channel_name)

    # Receive message from WebSocket
    async def receive(self, text_data):
        text_data_json = json.loads(text_data)
        message = text_data_json["message"]

        # Send message to room group
        await self.channel_layer.group_send(
            self.room_group_name, {"type": "chat.message", "message": message}
        )

    # Receive message from room group
    async def chat_message(self, event):
        message = event["message"]

        # Send message to WebSocket
        await self.send(text_data=json.dumps({"message": message}))

Error

Traceback (most recent call last):
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/django/contrib/staticfiles/handlers.py", line 101, in __call__
    return await self.application(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/routing.py", line 62, in __call__
    return await application(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/security/websocket.py", line 37, in __call__
    return await self.application(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/sessions.py", line 47, in __call__
    return await self.inner(dict(scope, cookies=cookies), receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/sessions.py", line 263, in __call__
    return await self.inner(wrapper.scope, receive, wrapper.send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/auth.py", line 185, in __call__
    return await super().__call__(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/middleware.py", line 24, in __call__
    return await self.inner(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/routing.py", line 116, in __call__
    return await application(
           ^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/consumer.py", line 94, in app
    return await consumer(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/consumer.py", line 62, in __call__
    await await_many_dispatch([receive], self.dispatch)
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/utils.py", line 50, in await_many_dispatch
    await dispatch(result)
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/consumer.py", line 73, in dispatch
    await handler(message)
  File "/Users/darklaki/Desktop/djnago-channels-learn/venv/lib/python3.12/site-packages/channels/generic/websocket.py", line 173, in websocket_connect
    await self.connect()
  File "/Users/darklaki/Desktop/djnago-channels-learn/chat/consumers.py", line 15, in connect
    await self.channel_layer.group_add(self.room_group_name, self.channel_name)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'group_add'
WebSocket DISCONNECT /ws/chat/hello/ [127.0.0.1:57473]
/Users/darklaki/Desktop/djnago-channels-learn/chat/consumers.py changed, reloading.

[Lawal Afeez]

hi @QuvonchbekBobojonov

The error is pointing towards channel_layer to be having an attribute of NoneType, are you sure you added the CHANNEL_LAYERS in your settings.py file ??

something like

CHANNEL_LAYERS = {
    "default": {
        "BACKEND": "channels_redis.core.RedisChannelLayer",
        "CONFIG": {
            "hosts": [('localhost', 6379)],
        }
    }
}