Django channels: Save messages to database

Question

I'm a newbie to channels and I made a chatroom application by following their official documentation. Now I'm trying to save the chat messages. All I know is I can create a model but Idk how to save it from the consumers.py into my database. I added username along with the message. A little help would be appreciated.

My Consumers.py:

import json
from channels.generic.websocket import AsyncWebsocketConsumer

class ChatConsumer(AsyncWebsocketConsumer):
    async def connect(self):
        self.room_name = self.scope['url_route']['kwargs']['room_name']
        self.room_group_name = 'chat_%s' % self.room_name

        # Join room group
        await self.channel_layer.group_add(
            self.room_group_name,
            self.channel_name
        )

        await self.accept()

    async def disconnect(self, close_code):
        # Leave room group
        await self.channel_layer.group_discard(
            self.room_group_name,
            self.channel_name
        )

    # Receive message from WebSocket
    async def receive(self, text_data):
        username = self.scope["user"].first_name
        name = self.scope['user'].username
        text_data_json = json.loads(text_data)
        message = text_data_json['message']
        message = (username + '(' + name + ')' + ':\n' + message)

        # Send message to room group
        await self.channel_layer.group_send(
            self.room_group_name,
            {   
                'type': 'chat_message',
                'message': message
            }
        )

    # Receive message from room group
    async def chat_message(self, event):
        username = self.scope["user"].username
        message = event['message']
        name = self.scope["user"].username

        # Send message to WebSocket
        await self.send(text_data=json.dumps({
            'message': message,
            "username": username,
            "name": name
        }))

My model to save the msgs:

class Message(models.Model):
    author = models.ForeignKey(User, related_name='messages', on_delete=models.CASCADE)
    context = models.TextField()
    timestamp = models.DateTimeField(auto_now_add=True)

I tried to follow this tutorial as well: https://www.youtube.com/watch?v=xrKKRRC518Y

Lanita

Did you manage to solve it? Can you help me with the solution you found? – Riggall

Answer 1

For the users who still have this issue:

Since the WebSocket being used is AsyncWebsocketConsumer, we have to use database_sync_to_async. Why so? Because we do not want to leave open connections to the database.

This is how you will do it:

@database_sync_to_async
def create_chat(self, msg, sender):
    Message.objects.create(sender=sender, msg=msg)

This is a simple example to demonstrate how to successfully use database_sync_to_async:

import json

from channels.db import database_sync_to_async
from channels.generic.websocket import AsyncWebsocketConsumer

from .models import Message


class ChatConsumer(AsyncWebsocketConsumer):
    @database_sync_to_async
    def create_chat(self, msg, sender):
        return Message.objects.create(sender=sender, msg=msg)

    async def connect(self):
        self.room_name = self.scope['url_route']['kwargs']['room_name']
        self.room_group_name = 'chat_%s' % self.room_name
        await self.channel_layer.group_add(self.room_group_name, self.channel_name)
        await self.accept()

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

    async def receive(self, text_data):
        text_data_json = json.loads(text_data)
        message = text_data_json['message']
        sender = text_data_json['sender']
        await self.channel_layer.group_send(self.room_group_name, {
            'type': 'chat_message',
            'message': message,
            'sender': sender
        })

    async def chat_message(self, event):
        message = event['message']
        sender = event['sender']
        new_msg = await self.create_chat(sender, message)  # It is necessary to await creation of messages
        await self.send(text_data=json.dumps({
            'message': new_msg.message,
            'sender': new_msg.sender
        }))

Hymnody

Answer 2

What's wrong with just creating the message regularly?

message = Message.objects.create(context=message, author=self.scope['user'])

Trichoid

Oh I didn't try that. I believe I should place it in the receive function right? – Lanita

I think so, yeah, not super experienced with channels but depending on where you do this, there is a possibility that you get duplicate messages. So you need to try it out. – Kalil

But this would give an error as it cannot be used in async context – Riggall

did you find out how to do this? I have excactly the same problem :/ – Autoerotic