Catch post_save signal

Question

Django 3.0.5.

apps.py

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

class NewsConfig(AppConfig):
    name = 'news'

    def ready(self):
        from .models import News # Breakpoint 0

        @receiver(post_save, sender=News)
        def handle_news_save(sender, **kwargs):
            print("Working")
            a = 0 # Breakpoint 1

models.py

class News(models.Model):
    news_text = models.TextField()

settings.py

INSTALLED_APPS = [
     ...
    'news.apps.NewsConfig',
]

The problem

At Breakpoint 0 the interpreter stops when I run the application. That is at the next line Django gets to know that I'm catching the signal.

But when I save an instance of News in admin site, at Breakpoint 1 the interpreter doesn't stop. And, of course, no printing happens. Could you help me catch the signal?

Answer 1

Ok i tried it out and played with signals a little, here's what i found out:

As the question state this way of defining does not work it seems to not register the signal correctly. I have no clue why it doesn't.

I guess the convention about signals would be anyways to move them to a signals.py file and then in the apps.py you only import them.

signals.py:

from .models import News  # Breakpoint 0
from django.db.models.signals import post_save
from django.dispatch import receiver


@receiver(post_save, sender=News)
def handle_news_save(sender, **kwargs):
    print("Working")
    a = 0  # Breakpoint 1

apps.py:

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


class PollsConfig(AppConfig):
    name = 'polls'

    def ready(self):
        import polls.signals

and then it works