Using django signals in channels consumer classes

Question

I am trying to develop an auction type system, where a customer makes an order, and then different stores can offer a price for that order.

An interesting part of this

Answer 1

If someone stumbles upon on that, this is the way I solved it in the signals.py. I have a Job and need to send its status to the client every time it changes. This is my signals.py:

import channels.layers
from asgiref.sync import async_to_sync

from django.db.models.signals import post_save
from django.dispatch import receiver

from .models import Job


def send_message(event):
    '''
    Call back function to send message to the browser
    '''
    message = event['text']
    channel_layer = channels.layers.get_channel_layer()
    # Send message to WebSocket
    async_to_sync(channel_layer.send)(text_data=json.dumps(
        message
    ))


@receiver(post_save, sender=Job, dispatch_uid='update_job_status_listeners')
def update_job_status_listeners(sender, instance, **kwargs):
    '''
    Sends job status to the browser when a Job is modified
    '''

    user = instance.owner
    group_name = 'job-user-{}'.format(user.username)

    message = {
        'job_id': instance.id,
        'title': instance.title,
        'status': instance.status,
        'modified': instance.modified.isoformat(),
    }

    channel_layer = channels.layers.get_channel_layer()

    async_to_sync(channel_layer.group_send)(
        group_name,
        {
            'type': 'send_message',
            'text': message
        }
    )

By the way, I have a Consumer class JobUserConsumer(AsyncWebsocketConsumer) where I define the groups:

async def connect(self):

    user = self.scope["user"]
    self.group_name = 'job-user-{}'.format(user.username)

    await self.channel_layer.group_add(
        self.group_name,
        self.channel_name
    )

    await self.accept()

The project I used this is here: https://github.com/ornl-ndav/django-remote-submission/tree/master/django_remote_submission