Question

我正在使用channels来实现WebSockets。我正在尝试通过websocket从post_save django信号发送数据。下面是我的代码。

signals.py

@receiver(post_save, sender=CheckIn)
def send_data_on_save(sender, instance, **kwargs):
    channel_layer = get_channel_layer()
    stats = get_stats()
    async_to_sync(channel_layer.group_send)(
            'dashboard',
            {
                'type': 'send_data',
                'message': stats
            }
        )

    analytics = get_analytics()
    async_to_sync(channel_layer.group_send)(
            'analytic',
            {
                'type': 'send_data',
                'message': analytics
            }
        )

consumers.py

class DashboardConsumer(WebsocketConsumer):
    def connect(self):
        self.room_group_name = 'dashboard'

        # 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': 'send_data',
                'message': message
            }
        )

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

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

同一段代码在我的本地计算机（windows）上运行，但是当我尝试在服务器上（ubuntu 16.04）运行此代码时，出现以下错误：

跟踪

Exception inside application: module 'asyncio' has no attribute '_get_running_loop'
    File "/usr/lib/python3.5/asyncio/tasks.py", line 241, in _step
        result = coro.throw(exc)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/channels/sessions.py", line 183, in __call__
        return await self.inner(receive, self.send)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/channels/middleware.py", line 41, in coroutine_call
        await inner_instance(receive, send)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/channels/consumer.py", line 59, in __call__
        [receive, self.channel_receive], self.dispatch
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/channels/utils.py", line 52, in await_many_dispatch
        await dispatch(result)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/asgiref/sync.py", line 145, in __call__
        return await asyncio.wait_for(future, timeout=None)
    File "/usr/lib/python3.5/asyncio/tasks.py", line 373, in wait_for
        return (yield from fut)
    File "/usr/lib/python3.5/asyncio/futures.py", line 361, in __iter__
        yield self  # This tells Task to wait for completion.
    File "/usr/lib/python3.5/asyncio/tasks.py", line 296, in _wakeup
        future.result()
    File "/usr/lib/python3.5/asyncio/futures.py", line 274, in result
        raise self._exception
    File "/usr/lib/python3.5/concurrent/futures/thread.py", line 55, in run
        result = self.fn(*self.args, **self.kwargs)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/channels/db.py", line 14, in thread_handler
        return super().thread_handler(loop, *args, **kwargs)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/asgiref/sync.py", line 164, in thread_handler
        return func(*args, **kwargs)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/channels/consumer.py", line 105, in dispatch
        handler(message)
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/channels/generic/websocket.py", line 39, in websocket_connect
        self.connect()
    File "/home/user1/demowebapps/vmsbackend/check_in/consumers.py", line 57, in connect
        self.channel_name
    File "/home/user1/demowebapps/env/lib/python3.5/site-packages/asgiref/sync.py", line 41, in __call__
        if asyncio._get_running_loop() is not None:
    module 'asyncio' has no attribute '_get_running_loop'

当我从javascript .send()函数正常发送数据时，它在服务器上也可以正常工作，但是当调用post_save信号时，只有我在服务器上收到此错误。这在我的本地系统上运行良好。我尝试从信号中删除async_to_sync，但它没有给出错误，但没有通过Web套接字传输数据。那么它给出了：

./check_in/signals.py:47: RuntimeWarning: Coroutine'RedisChannelLayer.group_send' was never awaited
'message': analytics

我在本地和服务器上都使用pythom 3.5.2。

我不知道怎么了。是代码还是其他。任何帮助表示赞赏。谢谢

Answer 1

从堆栈跟踪来看，asgiref正在访问私有异步函数_get_running_loop，以获取与旧Python版本中的3.7的get_running_loop等效的功能。但是您正在运行3.5.2，甚至没有私有功能。

尝试将Python升级到3.6或3.7，事情可能会起作用。

AttributeError：模块“ asyncio”没有属性“ _get_running_loop”

1 个答案: