Django Channels - 无法在断开连接时发送消息

Question

我希望能够在用户断开连接时向房间组发送消息，以便更新玩家列表。似乎一旦断开连接就不可能了，这在某种程度上是有道理的，但是我如何能够在通道断开用户连接之前向它发送消息。

我有以下代码：

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

这是一个老问题，我不知道是否还有人需要回答，但我发现的解决方案实际上在 Django Channels 3.0.1 中非常简单。每个WebsocketConsumer 都定义了一个websocket_disconnect 函数，该函数在调用实际的disconnect 函数之前删除当前分配给websocket 的组。显然，这意味着当您到达 disconnect 时，您将无法再发送群组消息，因为没有群组。

解决方案是简单地覆盖 websocket_disconnect 并将您的消息发送到那里，如下所示：

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