Suggestion: Raise a ValueError exception if receive()'s "channels" argument is not of type "list".

[danielniccoli]

Yes, I should have read the documentation more carefully, especially the part where it says

receive(channels, block=False), a callable that takes a list of channel names as unicode strings […]*

It was also tempting to write

channel_layer.send("my_channel", {"text": "Hello"})
channel_layer.receive("my_channel")

and pass a string to the receive method instead of a list, just as in the send() method

Took me a moment to figure out why I wouldn't receive any messages. In asgi_ipc.py#L67 the channels argument is passed to list() and therefore I was listening to a number of channels, but not to what I thought I were listening.

My suggestion is to raise a ValueError exception if the channels argument is not of type "list". Makes debugging a little quicker for those who happen to have overlooked that part in the docs.

* Source: https://channels.readthedocs.io/en/latest/asgi.html

[andrewgodwin]

Yes, this would be a sensible thing to check for. The base asgiref layer has functions to check channel names already, it's possibly something that could be rolled in there,

[navyad]

@andrewgodwin should assertion error be raised here like this ?

[andrewgodwin]

That would work, alternately make this (https://github.com/django/asgiref/blob/master/asgiref/base_layer.py#L104) have a version that validates multiple channels as a list.

[navyad]

@andrewgodwin list version validation method added https://github.com/django/asgiref/pull/8

[andrewgodwin]

Thanks, I've merged that in. I'll need to do a new asgiref release before a change can be landed for this as the dependency needs changing.

[navyad]

@andrewgodwin Cool.

[rixx]

Not really - the asgiref implementation of valid_channel_names does not offer the receive argument that we'd need to pass through here. This issue can be resolved via #24 once django/asgiref#18 is merged and released.