No route found for path 'call' in using webRTC

Question

I'm trying to make chat application by using websocket and I'm trying to connect to django-channels.

My consumers.py looks like this:

import json

from channels.generic.websocket import AsyncWebsocketConsumer


class VideoCallConsumer(AsyncWebsocketConsumer):
        
    async def connect(self):
        self.room_group_name = self.scope['url_route']['kwargs']['room_name']
        
        await self.channel_layer.group_add(
            self.room_group_name,
            self.channel_name
        )

        await self.accept()

    async def disconnect(self, code):
        
        await self.channel_layer.group_discard(
            self.room_group_name,
            self.channel_name
        )        

    async def receive(self, text_data):
        receive_dict = json.loads(text_data)
        action = receive_dict['action']
        ## 147
        if action == 'new-offer' or action == 'new-answer':
            
            receiver_channel_name = receive_dict['message']['receiver_channel_name']

            receive_dict['message']['receiver_channel_name'] = self.channel_name

            await self.channel_layer.send(
                receiver_channel_name,
                {
                    'type': 'send.sdp',
                    'receive_dict': receive_dict,
                }
            )

            return

        receive_dict['message']['receiver_channel_name'] = self.channel_name

        await self.channel_layer.group_send(
            self.room_group_name,
            {
                'type': 'send.sdp',
                'receive_dict': receive_dict,
            }
        )

    async def send_sdp(self, event):
        receive_dict = event['receive_dict']

        this_peer = receive_dict['peer']
        action = receive_dict['action']
        message = receive_dict['message']

        await self.send(text_data=json.dumps({
            'peer': this_peer,
            'action': action,
            'message': message,
        }))

My routing.py

from django.urls import re_path

from . import consumers

websocket_urlpatterns = [
    re_path(r'ws/call/<str:room_name>/', consumers.VideoCallConsumer.as_asgi()),
    #re_path(r'', consumers.VideoCallConsumer.as_asgi()),
]

My project routing.py:

import os
import call.routing

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

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'config.settings')

application = ProtocolTypeRouter({
  "http": get_asgi_application(),
  "websocket": AuthMiddlewareStack(
        URLRouter(
            call.routing.websocket_urlpatterns
        )
    ),
})

I tried to name room_group_name with self.scope['url_route']['kwargs']['room_name'].

The problem is, I can't connect to the websocket, my django server says: Exception inside application: No route found for path 'call'.

WebSocket HANDSHAKING /call [127.0.0.1:52045]
Exception inside application: No route found for path 'call'.
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/channels/staticfiles.py", line 44, in __call__
    return await self.application(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/channels/routing.py", line 71, in __call__
    return await application(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/channels/sessions.py", line 47, in __call__
    return await self.inner(dict(scope, cookies=cookies), receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/channels/sessions.py", line 263, in __call__
    return await self.inner(wrapper.scope, receive, wrapper.send)
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/channels/auth.py", line 185, in __call__
    return await super().__call__(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/channels/middleware.py", line 26, in __call__
    return await self.inner(scope, receive, send)
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/channels/routing.py", line 168, in __call__
    raise ValueError("No route found for path %r." % path)
ValueError: No route found for path 'call'.
WebSocket DISCONNECT /call [127.0.0.1:52045]

I want to know why this error raised

Also I have additional questions. I think send.sdp in consumers.py is a 'message' here, but what does it represent? And what is the structure of receive_dict in comsumers.py? receivedict['message']['receiverchannelname'] = self.channelname is in consumers.py and self.channel_name is not declared, but why is it working?