如何从django视图向消费者发送消息(django-channels)？

Question

我想从Django视图向django频道消费者发送一些消息。我有这样的消费者：

from channels.generic.websocket import AsyncWebsocketConsumer
import json

class KafkaConsumer(AsyncWebsocketConsumer):
    async def connect(self):
        self.room_group_name = 'kafka'

        # 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': 'kafka_message',
                'message': message
            }
        )

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

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

我的Django视图是这样的：

from django.views.generic import TemplateView
from django.http import HttpResponse

from channels.layers import get_channel_layer
from asgiref.sync import async_to_sync


class LogView(TemplateView):
    template_name = "kafka/index.html"


def testview(request):
    channel_layer = get_channel_layer()

    async_to_sync(channel_layer.group_send(
        'kafka',
        {
            'type': 'kafka.message',
            'message': 'Test message'
        }
    ))
    return HttpResponse('<p>Done</p>')

URL url类似于：

from django.urls import path
from .views import LogView, testview

urlpatterns = [
    path(r'', LogView.as_view()),
    path(r'test/', testview),

]

因此，当我执行http://mydevhost/test/时，消费者不会收到消息。但是，我可以从消费者发送消息，也可以在消费者内部发送消息，即在通道消费者中发送KafkaConsumer.receive。

Answer 1

在async_to_sync上犯了很愚蠢的错误。实际上，async_to_sync应该只包装channel_layer.group_send，而不是整个，即async_to_sync(channel_layer.group_send)。所以调用看起来像这样：

async_to_sync(channel_layer.group_send)(
    'kafka',
    {
        'type': 'kafka.message',
        'message': 'Test message'
    }
)

所有包含已更正代码的视图代码：

from django.views.generic import TemplateView
from django.http import HttpResponse

from channels.layers import get_channel_layer
from asgiref.sync import async_to_sync


class LogView(TemplateView):
    template_name = "kafka/index.html"


def testview(request):
    channel_layer = get_channel_layer()

    async_to_sync(channel_layer.group_send)(
        'kafka',
        {
            'type': 'kafka.message',
            'message': 'Test message'
        }
    )
    return HttpResponse('<p>Done</p>')