Consumers aren't designed to be run outside of a Channels or ASGI
environment. If you read the ASGI spec (
https://github.com/django/asgiref/blob/master/specs/asgi.rst), you'll see
that to run a consumer - which is an ASGI app - you need to do quite a bit
more than you did there, in particular making an event loop and running its
Instead, if you want to receive on a channel layer channel externally, I
recommend calling channel_layer.receive directly. It takes a channel name
to receive on and blocks until there's a message. Ideally you should do
this all within an async context rather than using async_to_sync, but I
believe both should work.
On Tue, Mar 13, 2018 at 12:15 AM, Alex <alexanderhalf...@gmail.com> wrote:
> The docs explain that it is possible to publish to the channel layer from
> outside of a consumer: https://channels.readthedocs.io/en/latest/
> topics/channel_layers.html#using-outside-of-consumers I need to do the
> opposite. I have a fairly complex python script that reads live data from
> pubnub, processes it, and pushes it to consumers via groups on the
> channel_layer. This works fine, but I need consumers to be able to announce
> their presence to this script so that it can push them data (it currently
> pushes to the channel layer only when it gets new data from pubnub, which
> could be every 24 hours).
> I've decided to solve this by having the consumers publish to a 'presence'
> channel on connect. I now need the pubnub source script to listen to this
> channel. I've tried adding the below to the script, and it no longer throws
> errors, but it doesn't actually respond to messages. It successfully joins
> the channel layer, but the message handler 'receive_json', never fires.
> This is the class, and then the initiation further down in the code:
> from channels.generic.websocket import JsonWebsocketConsumer
> class channelConsumer(JsonWebsocketConsumer):
> def __init__(self):
> self.channel_name = 'source'
> def join(self):
> async_to_sync(channel_layer.group_add)('presence', self.
> def receive_json(self, message):
> print("Presence Detected")
> # do some stuff
> global channel_layer
> channel_layer = get_channel_layer()
> global listener
> listener = channelConsumer()
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