group_send does not work for a model instance

[nebiyuelias1]

I am trying to use group_send using a model instance:

def group_send(moogt, notification):
    channel_layer = get_channel_layer()
    if moogt:
        async_to_sync(channel_layer.group_send)(f'{moogt.id}', notification)

Here notification, contains a model object like this:

notification = {
        'type': 'receive_group_message',
        'argument': argument,
        'event_type': message_type
    }

Of course, I do serialize the model object in the consumer, inside receive_group_message. But I am not getting anything in my websocket clients.

[pawel-czarnecki]

Actually I've encountered the same problem, my group doesn't received anything back while using group_send from channel_layer. I haven't seen any changes in docs about this topic. I'm using v3.0.2

[pawel26]

@nebiyuelias1 which version of channels are you using?

[nebiyuelias1]

channels==2.4.0

[sevdog]

group_send behaviour dependes on channel layer.

If you use InMemoryChannelLayer it is fine to leave model instances into messages. but if you use RedisChannelLayer (or any other channel layer which needs to interact with an external system) this is not possible anymore since message data needs to be serialized in the process. By default django model instances are not serializable by common used serializers (json/msgpack).

Of course, I do serialize the model object in the consumer, inside receive_group_message.

You also need to serialize the model in your group_send before passing to channel layer.

However I would expect some errors to be thrown like "unable to serialize instance of ", if you do not see any I suppose that the serializer you ara using is failing silently.

[carltongibson]

What @sevdog says is correct.

I don't think there's enough to really go on as a concrete issue.