Send events from management commands

Hey, I’m trying to implement SSE notifications endpoint . I have the routing setup as follows:

# asgi.py

application = ProtocolTypeRouter({
        "http": URLRouter(
            [
                re_path(r"", get_asgi_application()),
                re_path(
                    r"^notifications/(?P<user_address>0x[0-9A-Fa-f]+)/$",
                    URLRouter(django_eventstream.routing.urlpatterns),
                    {"format-channels": ["notifications-{user_address}"]},
                ),
            ]
        ),
    })


# urls.py

urlpatterns = [
    re_path(r"^notifications/(?P<user_address>0x[0-9A-Fa-f]+)/", include(django_eventstream.urls), {"format-channels": ["notifications-{user_address}"]})
]

The problem here is that I’d like to send the event (via send_event function) from separate management command, that handles the events and sending the notification and this management command runs on different process. I tried sending it directly from the management command, but unfortunately the event was not sent back to the client. If I understand this correctly, it’s due that runserver and event_listener management command run on different processes.

So if I understand properly, I need to somehow pass to the EventsConsumer class the info that this event happened using django channels and then send the event from this consumer? I was also playing around with extending the EventsConsumer, but unfortunately I was not able to implement this. If you have a spare minute and you have any idea how I could achieve this (sending events from managment commands), I’d greatly appreciate any help. Thanks!

P.S: I’ve tried Pushpin, seems to be working alright, but ideally we would stick to the channels for more “standard” deployment.

[microHoffman]

Hey @tommyxd , I’ve ended up not using django-eventstream, but rather just django-channels. I’ve utilized the channel layers for the interprocess communication. For the sse consumer itself, I got inspired here: django/channels#1302 (comment) .

I see, thanks for the pointer! So with that how do you send something from a management command to the consumer, are there any intricacies to it?

You just (im not an expert so hopefully this makes sense:D):

• define asgi application
• setup your subscription route (i’ve done it in routing in asgi.py). add a corresponding SseConsumer (the one taken form the django channels GH) to this route
• in the consumer, i am adding user to the group in handle method - like this await self.channel_layer.group_add(group_name, self.channel_name) - you can access the self.channel_layer in the SseConsumer directly
• then when i want to send events (e.g. from management command), I am using this group send:

        from channels.layers import get_channel_layer
        self.channel_layer = get_channel_layer()
        async_to_sync(self.channel_layer.group_send)(recipient_address, {"type": type, "data": data})

Hopefully this makes sense:D

[microHoffman]

@microHoffman Could you share some more details as how you managed to get the interprocess communication working? Thanks!

Hey @tommyxd , I’ve ended up not using django-eventstream, but rather just django-channels. I’ve utilized the channel layers for the interprocess communication. For the sse consumer itself, I got inspired here: https://github.com/django/channels/issues/1302#issuecomment-508896846 .