Thank you so much for the detailed explanation.
1) I now understand where my error was - the custom channel I used was
passing events to a background worker that was not related to the websocket
consumer. This also answers my question about how channel names must be
included in the runworker command explicitly, similar to celery.
2) To fix my own issue, all I had to do was add the group to the right
channel (*self.channel_name *in this case). I did read the multichat
example a few times but missed the reference to the implicit channel name.
I can now send messages to my front end app perfectly.
Andrew/Ken - Thank you for taking the time to assist and helping me solve
the issue.
On Sunday, February 25, 2018 at 2:56:45 AM UTC+2, muha...@swordfish.co.za
wrote:
>
> I'm still trying to find my way around channels 2.0, so I'm not sure if my
> implementation is incorrect or if this is a valid issue. I'm going to post
> as much info as possible in the hope that it will assist with finding the
> problem.
>
> I have a single page app which opens a JS websocket connection - with
> channels 1 I used to add a *session_key *to the querystring and that used
> to handle the authentication.
>
> I see this is no longer the case, so I now have a custom middleware class
> that sets the user object on the scope:
>
> from django.contrib.sessions.models import Session
>
> from users.models import User
>
>
> class QueryAuthMiddleware:
>
> def __init__(self, inner):
> # Store the ASGI application we were passed
> self.inner = inner
>
> def __call__(self, scope):
> # Look up user from query string (you should also do things like
> # check it's a valid user ID, or if scope["user"] is already
> populated)
> if scope.get("user", None) is None:
> session_obj =
> Session.objects.get(session_key=scope["query_string"].decode("utf-8").split("=")[1])
> session_decoded = session_obj.get_decoded()
>
> scope["user"] =
> User.objects.get(id=session_decoded.get("_auth_user_id"))
>
> # Return the inner application directly and let it run everything
> else
> return self.inner(scope)
>
>
>
>
> This is in turn added to my routing (channels.py):
>
> from django.conf.urls import url
> from django.conf import settings
> from channels.routing import ProtocolTypeRouter, URLRouter, ChannelNameRouter
>
> from notifications.consumer import TestWebsocketConsumer, TestConsumer
> from notifications.middleware.query_auth_middleware import QueryAuthMiddleware
>
> ROOT_PATH = "" if settings.DEBUG else "/ws/"
>
>
> application = ProtocolTypeRouter({
>
> "websocket": QueryAuthMiddleware(
> URLRouter([
> url(f"^{ROOT_PATH}(?P<user_id>[-\w]+)/$", TestWebsocketConsumer),
>
> ])
> ),
>
> "channel": ChannelNameRouter({
> "user-notifications": TestConsumer,
> })
>
>
> })
>
>
>
>
>
> Here's my *consumers.py*:
>
> from asgiref.sync import async_to_sync
> from channels.consumer import SyncConsumer
> from channels.generic.websocket import WebsocketConsumer
>
>
> class TestWebsocketConsumer(WebsocketConsumer):
> def websocket_connect(self, message):
>
> async_to_sync(self.channel_layer.group_add)(str(self.scope["user"].id),
> "user-notifications")
> self.connect()
>
>
> class TestConsumer(SyncConsumer):
> def notification_handler(self, message):
>
> self.send(
> {
> "type": "websocket.send",
> "text": message["text"]
> }
> )
>
>
>
>
>
>
> The idea of the app is that each user that logs in on the front end is
> able to receive messages meant only for them sent by the back end. I have
> been trying to test it like this:
>
> >>> channel_layer = get_channel_layer()
> >>> async_to_sync(channel_layer.send)("user-notifications", {"type":
> >>> "notification.handler", "text": "My Message"})
>
>
>
>
> Here's the traceback in the *runworker* output:
>
> 2018-02-25 02:34:14,002 - INFO - runworker - Running worker for channels
> ['user-notifications']
> ERROR:root:Exception inside application: You must implement
> application_send()
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/channels/consumer.py",
>
> line 54, in __call__
> await await_many_dispatch([receive, self.channel_receive],
> self.dispatch)
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/channels/utils.py",
> line 48, in await_many_dispatch
> await dispatch(result)
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/asgiref/sync.py",
> line 110, in __call__
> return await asyncio.wait_for(future, timeout=None)
> File
> "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/tasks.py",
>
> line 333, in wait_for
> return (yield from fut)
> File
> "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/concurrent/futures/thread.py",
>
> line 55, in run
> result = self.fn(*self.args, **self.kwargs)
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/channels/db.py",
> line 13, in thread_handler
> return super().thread_handler(loop, *args, **kwargs)
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/asgiref/sync.py",
> line 125, in thread_handler
> return self.func(*args, **kwargs)
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/channels/consumer.py",
>
> line 99, in dispatch
> handler(message)
> File
> "/Users/muhammed/projects/xxx/my-app/app/notifications/consumer.py", line
> 18, in notification_handler
> "text": message["text"]
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/channels/consumer.py",
>
> line 107, in send
> self.base_send(message)
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/asgiref/sync.py",
> line 64, in __call__
> return call_result.result()
> File
> "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/concurrent/futures/_base.py",
>
> line 405, in result
> return self.__get_result()
> File
> "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/concurrent/futures/_base.py",
>
> line 357, in __get_result
> raise self._exception
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/asgiref/sync.py",
> line 78, in main_wrap
> result = await self.awaitable(*args, **kwargs)
> File
> "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/asgiref/server.py",
> line 71, in application_send
> raise NotImplementedError("You must implement application_send()")
> You must implement application_send()
>
>
> OS: MacOS High Sierra
> Python: 3.6.1
>
> Django==2.0.2
> channels==2.0.2
> channels-redis==2.1.0
> asgiref==2.1.6
> daphne==2.0.4
>
> Config from *settings.py:*
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> *# -- Channels DetailsCHANNEL_LAYERS = { "default": { "BACKEND":
> "channels_redis.core.RedisChannelLayer", "CONFIG": { "hosts":
> [("localhost", 6379)] } }}ASGI_APPLICATION =
> "myapp.settings.channels.application"*
>
> Any help would be appreciated.
>
>
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