python之信号和 django channel 聊天室

嗨，我正在努力让两件事同时工作......

channels2 chat room例子可以开始，但我想添加一个功能，知道房间里有多少人。我通过更新房间模型来做到这一点。

然后我想要一个仪表板来显示当前最受欢迎的房间，我想再次使用 channel 进行更新。 我使用了 django 信号方法，这种方法可以在没有人使用聊天时更新模型。

但是，当有人加入聊天时查看仪表板是否更新时出现错误。

    2018-05-11 19:19:09,634 - ERROR - server - Exception inside application: You cannot use AsyncToSync in the same thread as an async event loop - just await the async function directly. 
  File "/dev/channels_sk/channels-master/channels/consumer.py", line 54, in __call__ 
    await await_many_dispatch([receive, self.channel_receive], self.dispatch) 
  File "/dev/channels_sk/channels-master/channels/utils.py", line 50, in await_many_dispatch 
    await dispatch(result) 
  File "/dev/channels_sk/channels-master/channels/consumer.py", line 67, in dispatch 
    await handler(message) 
  File "/dev/channels_sk/channels-master/channels/generic/websocket.py", line 173, in websocket_connect 
    await self.connect() 
  File "/dev/channels_sk/tables/consumers.py", line 19, in connect 
    room.save() 
  File "/dev/channels_sk/.env/lib/python3.6/site-packages/django/db/models/base.py", line 729, in save 
    force_update=force_update, update_fields=update_fields) 
  File "/dev/channels_sk/.env/lib/python3.6/site-packages/django/db/models/base.py", line 769, in save_base 
    update_fields=update_fields, raw=raw, using=using, 
  File "/dev/channels_sk/.env/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 178, in send 
    for receiver in self._live_receivers(sender) 
  File "/dev/channels_sk/.env/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 178, in <listcomp> 
    for receiver in self._live_receivers(sender) 
  File "/dev/channels_sk/tables/signals.py", line 20, in room_save_handler 
    'update': instance.population, 
  File "/dev/channels_sk/.env/lib/python3.6/site-packages/asgiref/sync.py", line 34, in __call__ 
    "You cannot use AsyncToSync in the same thread as an async event loop - " 
  You cannot use AsyncToSync in the same thread as an async event loop - just await the async function directly.  

消费者.py

from channels.generic.websocket import AsyncWebsocketConsumer 
import json 
import time 
from .models import Room 
from django.db.models import F 
 
class ChatConsumer(AsyncWebsocketConsumer): 
    async def connect(self): 
        self.room_name = self.scope['url_route']['kwargs']['room_name'] 
        self.room_group_name = 'chat_%s' % self.room_name 
 
        # create room or increment 
        room, created = Room.objects.get_or_create(title=self.room_name) 
        pop = room.population + 1 
        room.population = F('population') + 1 
        room.save() 
 
        # Join room group 
        await self.channel_layer.group_add( 
            self.room_group_name, 
            self.channel_name 
        ) 
 
        await self.accept() 
 
        # send new population to group 
        await self.channel_layer.group_send( 
            self.room_group_name, 
            { 
            'type': 'pop_message', 
            'population': pop, 
            } 
        ) 
 
    async def disconnect(self, close_code): 
        room = Room.objects.get(title=self.room_name) 
        pop = room.population - 1 
        if room.population == 1: 
            if room.permanent == False: 
                room.delete() 
        else: 
            room.population = F('population') - 1 
            room.save() 
 
        # send new population to room group 
        await self.channel_layer.group_send( 
            self.room_group_name, 
            { 
            'type': 'pop_message', 
            'population': pop, 
            } 
        ) 
 
        # 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({ 
            # 'type': 'chat_message', 
            'message': message, 
        })) 
 
    # change in room group population 
    async def pop_message(self, event): 
        content = event['type'] 
        population = event['population'] 
 
        # Send message to WebSocket 
        await self.send(text_data=json.dumps({ 
            # 'type': 'pop_message', 
            'content': content, 
            'population': population, 
 
        })) 
 
 
class RoomConsumer(AsyncWebsocketConsumer): 
    async def connect(self): 
        self.group_name = 'chat_room_dash' 
        print("joined dash room") 
 
        # Join room group 
        await self.channel_layer.group_add( 
            self.group_name, 
            self.channel_name 
        ) 
 
        await self.accept() 
 
    async def disconnect(self, close_code): 
        print("left dash room") 
        pass 
 
    async def send_message(self, text_data=None): 
        print(text_data) 
        labels = [] 
        data = [] 
        for room in Room.objects.all()[:3]: 
            labels.append(room.title) 
            data.append(room.population) 
 
        await self.send(text_data=json.dumps( 
        { 
            'labels': labels, 
            'data': data, 
 
        }))  

信号.py

from django.db.models.signals import post_save 
from django.dispatch import receiver 
from channels.layers import get_channel_layer 
from asgiref.sync import async_to_sync 
 
 
 
from .models import Room 
 
 
@receiver(post_save, sender=Room) 
def room_save_handler(sender, instance, **kwargs): 
    channel_layer = get_channel_layer() 
    async_to_sync(channel_layer.group_send)( 
        'chat_room_dash', 
        { 
            'type': 'send_message', 
            'update': instance.population, 
        } 
    ) 

到目前为止

在阅读错误时，我尝试了建议的解决方案，方法是将 signals.py room_save_handler() 更改为异步并等待消息发送到群组。

然而，当我手动更新模型或当用户进入聊天室时，这并没有发送消息。

我的客人是，当第一个消费者调用 room.save() 时，room_save_handler() 也被调用，这意味着异步调用中有一个异步调用。

任何帮助都会很棒!

请您参考如下方法:

我有同样的问题，我已经在下面解决了 way :

import asyncio 
 
from django.db.models.signals import post_save 
from django.dispatch import receiver 
from channels.layers import get_channel_layer 
 
 
from .models import Room 
 
 
@receiver(post_save, sender=Room) 
def room_save_handler(sender, instance, **kwargs): 
    channel_layer = get_channel_layer() 
    loop = asyncio.get_event_loop() 
 
    coroutine = async_to_sync(channel_layer.group_send)( 
        'chat_room_dash', 
        { 
            'type': 'send_message', 
            'update': instance.population, 
        } 
    ) 
    loop.run_until_complete(coroutine)