Exception inside application: object.__init__() takes exactly one argument (the instance to initialize)

In Channels version 3.0.0 python raise exception when I try connect by websocket to my Django Application . Console log from runserver:

November 01, 2020 - 13:18:04
Django version 3.1.2, using settings 'Menu.settings'
Starting ASGI/Channels version 3.0.0 development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
WebSocket HANDSHAKING /ws/dist [127.0.0.1:56024]
Exception inside application: object.__init__() takes exactly one argument (the instance to initialize)
Traceback (most recent call last):
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/channels/routing.py", line 71, in __call__
    return await application(scope, receive, send)
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/channels/sessions.py", line 47, in __call__
    return await self.inner(dict(scope, cookies=cookies), receive, send)
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/channels/sessions.py", line 172, in __call__
    return await self.inner(self.scope, receive, self.send)
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/channels/auth.py", line 181, in __call__
    return await super().__call__(scope, receive, send)
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/channels/middleware.py", line 26, in __call__
    return await self.inner(scope, receive, send)
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/channels/routing.py", line 150, in __call__
    return await application(
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/asgiref/compatibility.py", line 33, in new_application
    instance = application(scope)
  File "/home/nakmak98/source/Menu/pycharm_venv/lib/python3.8/site-packages/channels/generic/websocket.py", line 23, in __init__
    super().__init__(*args, **kwargs)

My code:

index.js var ws = new WebSocket( 'ws://' + window.location.host + '/ws/dist')

routing.py

from django.urls import path

from . import consumers

websocket_urlpatterns = [
    path('ws/dist', consumers.MealPointConsumer),
]

When I run my code on previous version of Channels, it works great.

Django version 3.1.2, using settings 'Menu.settings'
Starting ASGI/Channels version 2.4.0 development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
HTTP GET /dist/ 200 [0.14, 127.0.0.1:55192]
...
WebSocket HANDSHAKING /ws/dist [127.0.0.1:55196]
WebSocket CONNECT /ws/dist [127.0.0.1:55196]

My OS: Linux Mint 19.3 pip freeze output:

aioredis==1.3.1
asgiref==3.2.10
async-timeout==3.0.1
attrs==20.2.0
autobahn==20.7.1
Automat==20.2.0
cffi==1.14.3
channels==3.0.0
channels-redis==3.2.0
constantly==15.1.0
cryptography==3.2.1
daphne==3.0.0
Django==3.1.2
hiredis==1.1.0
hyperlink==20.0.1
idna==2.10
incremental==17.5.0
msgpack==1.0.0
Pillow==8.0.1
pkg-resources==0.0.0
pyasn1==0.4.8
pyasn1-modules==0.2.8
pycparser==2.20
PyHamcrest==2.0.2
pyOpenSSL==19.1.0
pytz==2020.1
service-identity==18.1.0
six==1.15.0
sqlparse==0.4.1
Twisted==20.3.0
txaio==20.4.1
zope.interface==5.1.2

[carltongibson]

v3 is a big update to ASGI v3, which changes the signuature of consumers.

path('ws/dist', consumers.MealPointConsumer),

Here you need to add the new as_asgi() call when routing your consumer.

See the 3.0 release notes for more details and guidance on updating: https://channels.readthedocs.io/en/stable/releases/3.0.0.html#update-to-asgi-3

You should also probably review the docs, and update to routing.py to asgi.py as you go, to fall in-line with Django’s conventions.

I’ll leave this open for the now in case others bump into similar issues.

That release notes link again: https://channels.readthedocs.io/en/stable/releases/3.0.0.html#update-to-asgi-3

[jihoon796]

@carltongibson it took forever to find your comment, but adding as_asgi() saved me a lot of time. Thanks!