consumers.py
class NotificationConsumer(WebsocketConsumer):
    def connect(self):
        if self.scope["user"].is_anonymous:
            self.close()
        else:
            self.group_name = "user_id_" + str(self.scope["user"].id)
            async_to_sync(self.channel_layer.group_add)(
                self.group_name, self.channel_name
            )
            self.accept()

    def disconnect(self, close_code):
        self.close()

    def notify(self, event):
        self.send(text_data=json.dumps(event["text"]))