Checking if self.groups is None in AsyncWebsocketConsumer causes ValueError

[utsdanielosborne]

With reference to:

channels/channels/generic/websocket.py

Line 160 in ece488b

if self.groups is None:

The check of self.groups during _init_, to change it from None to an empty list 'if not set', causes a ValueError to be thrown by:

channels/channels/auth.py

Line 146 in ece488b

raise ValueError("Accessing scope user before it is ready.")

if self.groups is a property which tries to access scope['user'].

i.e.

class Test (AsyncWebsocketConsumer):

    @property
    def groups (self):
        return [a_fn(self.scope['user']]

Because scope['user'] is only set during _call_

I've had to work around this by catching ValueError in groups for when it's called from _init_

It seems to me that the _init_ check is only intended to ensure that self.groups returns a list, but does not need to access that list itself as it currently does.
Therefore this problem could be avoided perhaps by e.g defining a default groups property on AsyncWebsocketConsumer that can be overridden, and removing the two lines from _init_.

i.e.

class AsyncWebsocketConsumer (AsyncConsumer):

    @property
    def groups (self):
        ## Override as required.
        return []

    ## Removed def __init__(self, *args, **kwargs):

[aryaniyaps]

Hello @utsdanielosborne
Sorry for the late reply, but I think that the best way to set the groups attribute with reference to the scope's user would be to override the consumer's connect method. Here's an example.

class Test (AsyncWebsocketConsumer):
    async def connect(self):
        # reject anonymous connections if the
        # scope's user shouldn't be anonymous
        await self.accept()
        self.groups = [a_fn(self.scope['user']]

This way, you're guaranteed that the request's user would be set.

[aryaniyaps]

As far as I know, the groups attribute is only for setting "predefined" group names, which don't reference any attributes of the scope itself.