You are entirely right, Ken - the problem here is that "self.send()" on consumers where their scope type is "channel" is not defined. I suspect we could do with a better error message in this case rather than the one shown here.
The confusion probably comes as this would sort have worked in Channels 1, but in Channels 2, the only consumer that can send to a websocket is the one that's attached to it. All anything else can do is send messages over the channel layer to the websocket consumer to trigger _it_ to run code and send something.
Andrew
On Sat, Feb 24, 2018 at 6:08 PM, Ken Whitesell <kenwhitesell@comcast.net> wrote:
I'm going to take a stab at this - with the warning that I'm extremely uncertain that I'm anywhere close to being correct, but I'm hoping that I'm at least close enough that it might give you some clues.So where I think the issue may be is that you're trying to do a "self.send" from a worker task, not from a websocket task. If you look at the docs for the "Worker and Background Tasks", you'll see that to send an event you call "self.channel_layer.send" with a first parameter of the channel to which you wish to send the message.Since this worker task isn't running in the context of a websocket consumer, it doesn't automatically know to which channel a response should be sent. (I _know_ that my wording there is imprecise and probably inaccurate, but I think I'm sufficiently close for casual conversation.)If you want the worker task to send a message back to a client, what _I_ have done is create another method in my WebSocket consumer that takes a message and forwards it back out to the client. In thinking about it, I guess it may be possible that if I pass something (whatever that "something" might be) to the worker task, I might be able to send a message back out without going back through the consumer - again, that's a guess for something I haven't tried yet.Anyway, I hope this helps.Ken
On Saturday, February 24, 2018 at 7:56:45 PM UTC-5, 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)
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,
})
})
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"]
}
)
>>> async_to_sync(channel_layer.send)("user-notifications", {"type": "notification.handler", "text": "My Message"}) lib/python3.6/site-packages/ch annels/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/ch annels/utils.py", line 48, in await_many_dispatch await dispatch(result)File "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/as giref/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/ch annels/db.py", line 13, in thread_handler return super().thread_handler(loop, *args, **kwargs)File "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/as giref/sync.py", line 125, in thread_handler return self.func(*args, **kwargs)File "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/ch annels/consumer.py", line 99, in dispatch handler(message)File "/Users/muhammed/projects/xxx/my-app/app/notifications/consu mer.py", line 18, in notification_handler "text": message["text"]File "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/ch annels/consumer.py", line 107, in send self.base_send(message)File "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/as giref/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._exceptionFile "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/as giref/sync.py", line 78, in main_wrap result = await self.awaitable(*args, **kwargs)File "/Users/muhammed/projects/xxx/lib/python3.6/site-packages/as giref/server.py", line 71, in application_send raise NotImplementedError("You must implement application_send()")You must implement application_send()OS: MacOS High SierraPython: 3.6.1Django==2.0.2channels==2.0.2channels-redis==2.1.0asgiref==2.1.6daphne==2.0.4Config from settings.py:# -- Channels Details
CHANNEL_LAYERS = {
"default": {
"BACKEND": "channels_redis.core.RedisChannelLayer" ,
"CONFIG": {
"hosts": [("localhost", 6379)]
}
}
}
ASGI_APPLICATION = "myapp.settings.channels.application"
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