Django Channels - Not Able to Send Messages on Disconnect

Question

I would like to be able to send a message to the room group on disconnect of the user so that it updates the player list. It seems that it is not possible once disconnected, which would make sense in a way, but how would I be able to send a message to the channel before it disconnects the user.

I have the following code:

async def disconnect(self, close_code):
    #Remove the disconnected player
    player = players.get_player(self.scope['session']['id'])
    players.remove_player(player.id)
    room = rooms.get_room(player.room)
    if room:
        #Sending messages on disconnect doesn't seem to work
        players_left = room.leave_room(player)
        if players_left < 1:
            rooms.remove_room(room.name)
            await self.channel_layer.group_send(
                'all_users',
                {
                    'type': 'room_list',
                }
            )
            await self.channel_layer.group_discard(
                room.name,
                self.channel_name
            )
        else:
            await self.send_room(room,'list_players')
            
async def send_room(self,room,type):
    await self.channel_layer.group_send(
        room.name,
        {
            'type': type,
            'data': room.name
        }
    )

async def list_players(self,event):
    # Send message to WebSocket
    room = rooms.get_room(event['data'])
    players = room.get_players()
    await self.send(text_data=json.dumps({
        'action': 'room_list_players',
        'payload' : {
            'players' : players,
            'owner' : room.owner.id
        }
    }))

Answer 1

This is an old question and I don't know if anyone still needs it answered, but the solution that I found is actually pretty easy in Django Channels 3.0.1. Each WebsocketConsumer has a websocket_disconnect function defined which removes the groups currently assigned to the websocket before calling the actual disconnect function. Obviously this means by the time you get to disconnect you can't send group messages anymore as there are no groups.

The solution is to simply override websocket_disconnect and send your message there with something like this:

async def websocket_disconnect(self, message):
  await self.channel_layer.group_send(
    self.room_group_name,
    { 'type': 'dc_message' }
  )
  await super().websocket_disconnect(message)