Troubleshooting

ImproperlyConfigured exception

django.core.exceptions.ImproperlyConfigured: Requested setting INSTALLED_APPS, but settings are not configured.
You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.

This exception occurs when your application tries to import any models before Django finishes its initialization process aka django.setup().

django.setup() should be called only once, and should be called manually only in case of standalone apps. In context of Channels usage, django.setup() is called automatically in get_asgi_application(), which means it needs to be called before any ORM models are imported.

The working code order would look like this:

import os

from channels.auth import AuthMiddlewareStack
from channels.routing import ProtocolTypeRouter, URLRouter
from django.conf.urls import url
from django.core.asgi import get_asgi_application

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")
# Initialize Django ASGI application early to ensure the AppRegistry
# is populated before importing code that may import ORM models.
django_asgi_app = get_asgi_application()

from chat.consumers import AdminChatConsumer, PublicChatConsumer

application = ProtocolTypeRouter({
    # Django's ASGI application to handle traditional HTTP requests
    "http": django_asgi_app,

    # WebSocket chat handler
    "websocket": AuthMiddlewareStack(
        URLRouter([
            url(r"^chat/admin/$", AdminChatConsumer.as_asgi()),
            url(r"^chat/$", PublicChatConsumer.as_asgi()),
        ])
    ),
})