need more documents for groups_for_signal and groups_for_consumer, and what "__" means in the examples

[Randix6644]

what are groups_for_signal and groups_for_consumer for? I've read the documents but still have no clue about them. And I don't get what " f'chat{instance}'" means in the example, what does "" mean in this case?

[hishnash]

@Randix6644 could you link to the example in question.

[johnthagen]

I assume @Randix6644 is referring to the examples in the README here:

• https://github.com/NilCoalescing/djangochannelsrestframework/blob/master/README.rst#subscribing-to-a-signal

# consumers.py
from djangochannelsrestframework.consumers import AsyncAPIConsumer
from djangochannelsrestframework.decorators import action
from djangochannelsrestframework.observer import observer
from rest_framework import status
from .signals import joined_chat_signal
from .serializers import UserSerializer

class TestConsumer(AsyncAPIConsumer):

    @action()
    def join_chat(self, chat_id, **kwargs):
        serializer = UserSerializer(instance=self.scope['user'])
        joined_chat_signal.send(sender='join_chat', data=serializer.data, **kwargs)
        return {}, status.HTTP_204_NO_CONTENT

    @observer(signal=joined_chat_signal)
    async def joined_chat_handler(self, data, observer=None, action=None, subscribing_request_ids=[], **kwargs):
        for request_id in subscribing_request_ids:
            await self.reply(action='joined_chat', data=data, status=status.HTTP_200_OK, request_id=request_id)

    @joined_chat_handler.serializer
    def join_chat_handler(self, sender, data, **kwargs): # the data comes from the signal.send and will be available in the observer
        return data

    @joined_chat_handler.groups_for_signal
    def joined_chat_handler(self, instance, **kwargs):
        yield f'chat__{instance}'

    @joined_chat_handler.groups_for_consumer
    def joined_chat_handler(self, chat, **kwargs):
        if chat:
            yield f'chat__{chat}'

    @action()
    async def subscribe_joined(self, chat_id, request_id, **kwargs):
        await self.joined_chat_handler.subscribe(chat_id, request_id=request_id)