Sending data to django channels groups via django views

Question

TL;DR

Want this flow:

                     ws://...
websocket client 1 <-----------> websocket client 2
                         ^
                         |
                       server (send messages via views)

So I have the following:

views.py

def alarm(request):
    layer = get_channel_layer()
    async_to_sync(layer.group_send)('events', {
    'type': 'events.alarm',
    'content': 'triggered'
    })
    return HttpResponse('<p>Done</p>')

consumers.py

class EventConsumer(JsonWebsocketConsumer):
  def connect(self):
    print('inside EventConsumer connect()')
    async_to_sync(self.channel_layer.group_add)(
        'events',
        self.channel_name
    )
    self.accept()

  def disconnect(self, close_code):
    print('inside EventConsumer disconnect()')
    print("Closed websocket with code: ", close_code)
    async_to_sync(self.channel_layer.group_discard)(
        'events',
        self.channel_name
    )
    self.close()

  def receive_json(self, content, **kwargs):
    print('inside EventConsumer receive_json()')
    print("Received event: {}".format(content))
    self.send_json(content)

  def events_alarm(self, event):
    print('inside EventConsumer events_alarm()')
    self.send_json(
        {
            'type': 'events.alarm',
            'content': event['content']
        }
    )

in routing.py

application = ProtocolTypeRouter({
    'websocket': AllowedHostsOriginValidator(
        AuthMiddlewareStack(
            URLRouter(
                chat.routing.websocket_urlpatterns,

            )
        )
    ),
})

where websocket_urlpatterns is

websocket_urlpatterns = [
url(r'^ws/chat/(?P<room_name>[^/]+)/$', consumers.ChatConsumer),
url(r'^ws/event/$', consumers.EventConsumer),
]

urls.py

urlpatterns = [
    url(r'^alarm/$', alarm, name='alarm'),
]

when I call /alarm/ , only the HTTP request is made and the message is not sent to the websocket

The following are the logs:

[2018/09/26 18:59:12] HTTP GET /alarm/ 200 [0.07, 127.0.0.1:60124]

My intention is to make django view send to a group (use case would be for a server to send notification to all connected members in the group).

What setting am I missing here.

I am running django channels 2.1.3 with redis as backend. The CHANNELS_LAYERS etc. have all been setup.

Reference Links:

1. sending messages to groups in django channels 2
2. github issue
3. channels docs

EDIT: I could send the message using the websocket-client from the view

from websocket import create_connection
ws = create_connection("ws://url")
ws.send("Hello, World")

But is it possible to send without using the above (donot wan't to create a connection)?

Source code: chat-app

Answer 1

credits to @Matthaus Woolard for making the concept pretty clear.

So this was the problem:

The client had disconnected when I tried to send the message from the django view. This happened as the server restarted upon code change. I refreshed the browser and it started to work.

Silly mistake

So to summarize:

Add the following in connect() in case of Synchronous consumer:

async_to_sync(self.channel_layer.group_add)('events', self.channel_name)

or add this incase of Async Consumer:

await self.channel_layer.group_add('events', self.channel_name)

create a view as follows:

def alarm(request):
   layer = get_channel_layer()
   async_to_sync(layer.group_send)('events', {
           'type': 'events.alarm',
           'content': 'triggered'
        })
   return HttpResponse('<p>Done</p>')