example-in-django-waiting-room-for-asynchronous-tasks/waiting_room/consumers.py

import json
from channels.generic.websocket import WebsocketConsumer
from asgiref.sync import async_to_sync
from waiting_room.tasks import calculate_min_distance

class MyConsumer(WebsocketConsumer):

    def connect(self):
        self.room_group_name = self.scope["url_route"]["kwargs"]["room_name"]
        async_to_sync(self.channel_layer.group_add)(self.room_group_name, self.channel_name)
        self.accept()

    def disconnect(self, close_code):
        async_to_sync(self.channel_layer.group_discard)(self.room_group_name, self.channel_name)
        self.close()

    def receive(self, text_data):
        json_data = json.loads(text_data)
        # Echo
        self.send(text_data=text_data)
        # Run task
        if json_data['task'] == 'calculate':
            calculate_min_distance(self.room_group_name)

    def channel_message(self, event):
        message = event['message']

        # Send message to WebSocket
        self.send(text_data=str(message))