Django Channels Model Binding not sending messages

[Zac Kwan]

In production, I have setup asgi, wsgi and nginx. My javascript frontend manage connected successfully base on the logs in runworker. However, when a new model is created (DRF API, Admin or Shell), it does not send a message to the group where my frontend is connected. It work perfectly in runserver.

I had did some testing in the python manage.py shell and found out that it work when I try to send a group message myself first.

$ python manage.py shell

Python 3.6.2 (default, Aug 27 2017, 18:32:19)

[GCC 4.2.1 Compatible Apple LLVM 8.1.0 (clang-802.0.42)] on darwin

Type "help", "copyright", "credits" or "license" for more information.

(InteractiveConsole)

>>> from channels import Group
>>> from github_hook.models import Feed
>>>
>>> Feed.objects.create(name="foo") # Model is created but frontend did not receive any message
>>>
>>> Group("news").send({"text": "dsa"}) # After I do this, a print I had in consumers.py happened
>>> consumers.py is run!
>>>
>>>  Feed.objects.create(name="foo") # Now when i created a new object, frontend successfully received the mssage

The following is my CHANNEL_LAYERS setup:

CHANNEL_LAYERS = {

    "default": {

        "BACKEND": "asgi_redis.RedisChannelLayer",

        "CONFIG": {

            "hosts": [os.environ.get('REDIS_URL', 'redis://localhost:6379')],

        },

        "ROUTING": "github_hook.routing.channel_routing",

    },

}

I had been on this for 2 weeks, still caa't figure out what is wrong. Can anyone help me figure out whats wrong? 

It seems to me that my application that is served by WSGI, when created a model via admin, it does not trigger the message sending. It seems to be missing some init on consumers.py? 

[Andrew Godwin]

That is odd behaviour - have you tried to see if it's actually the group send, or something like trying to send it twice? Can you post your binding configuration?

Andrew

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[Zac Kwan]

I have a console.log in my javascript that verified is the newly created Feed that got sent. This is my binding, consumers and routing class:

#bindings.py
class FeedBinding(WebsocketBinding):

    model = Feed

    stream = "feed"

    fields = ["__all__"]

    @classmethod

    def group_names(cls, instance):

        return ["feed-grp", ]

    def has_permission(self, user, action, pk):

                return True

# consumers.py

class Demultiplexer(WebsocketDemultiplexer):

        print("consumers.py is run")

    consumers = {

        "feed": FeedBinding.consumer,

    }

        def connection_groups(self):

        return ["feed-grp", ]

# routing.py

channel_routing = [

    route_class(Demultiplexer, path="^/binding/"),

]

I still couldn't get the sending to work via admin or DRF API call when creating a `Feed` object. This somehow only happens in the production setup, runserver works fine.

Really appreciate your help, thanks for the great library!

Cheers

Zac

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[Zac Kwan]

For now, I manage to get it to work in production if I added the following to my `apps.py`.

#apps.py

from django.apps import AppConfig

class HookConfig(AppConfig):

    name = 'hook_app'

    def ready(self):

        import hook_app.signals

        # only need to do this for production so that when binding model is created it send out to group

        # not sure why, question is asked here: https://groups.google.com/forum/#!searchin/django-users/django$20channels|sort:date/django-users/10MPS5RFuAs/TuFI4sqIBAAJ

        from channels import Group

        Group("Test")

It seems to be some init for channels is missing. After I added the above, creating my models via admin or DRF works, it sends out the message to the correct group defined in my consumers.py. 

Although it works for my production server now, I am still unsure why it happens only in my production environment but not runserver. If anyone knows why, please reply. Thanks!