POST Request Fails to Trigger WebSocket Message in Django Production

Hello everyone,

I have a Django project where a POST request saves data into the database and then sends the updated content to a WebSocket. This works perfectly using the Django development server, but in production (nginx, uwsgi, and daphne) the WebSocket does not receive the updated data, although the database update happens without issue.

Interestingly, WebSocket communication works fine when data is received directly over the WebSocket. The problem only occurs when a POST request is used to trigger the send to the WebSocket. I’m looking for insights into why this discrepancy exists between production and development, or if there’s something unique about the interplay between POST requests and WebSocket sends in a production environment.

Below is the relevant code from my views.py and consumers.py files:

PYTHONCopied
from django.shortcuts import render
from django.template.loader import render_to_string
from asgiref.sync import async_to_sync
from channels.layers import get_channel_layer
from django.utils import timezone
from datetime import datetime
from .models import Loesung

def loesungsUpdate():
    loesungen = Loesung.objects.all()
    if loesungen:
        for i in loesungen:
            i.abgabezeit = datetime.fromisoformat(str(i.abgabezeit)).astimezone(timezone.get_current_timezone()).strftime("%d.%m.%Y, %H:%M")
        loesungen = render_to_string('mathenacht/partials/loesungsuebersichtUpdate.html', {'loesungen':loesungen})
        channel_layer = get_channel_layer()
        async_to_sync(channel_layer.group_send)(
            'loesungsuebersicht', {
                'type': 'loesungsuebersichtUpdateHandler', # Handler must be in consumers.py
                'loesungen': loesungen,
            }
        )

PYTHONCopied
from channels.generic.websocket import WebsocketConsumer
from asgiref.sync import async_to_sync
from django.template.loader import render_to_string
from django.utils import timezone
from datetime import datetime
import json
from .models import Loesung

class mathenachtConsumer(WebsocketConsumer):
    def connect(self):
        async_to_sync(self.channel_layer.group_add)(  # Add the connecting user to a 'backend' chatroom so that everyone receives every message
            'loesungsuebersicht', self.channel_name # chatroom as a hardcoded name for the chatroom, self.channel_name gets auto filled from Django and is tied to the user
        )
        self.accept()

    def disconnect(self, code):
        async_to_sync(self.channel_layer.group_discard)(  # Remove the user from that chatroom
            'loesungsuebersicht', self.channel_name
        )
    
    def receive(self, text_data):
        ...

    def loesungsuebersichtUpdateHandler(self, event):
        self.send(text_data=event['loesungen'])

I removed the code from the receive function in consumers.py as it is not relevant to the issue.

I appreciate any insights or suggestions on what might be causing this discrepancy in production. Thanks in advance!