How do I use signals in Django?

How do I use signals in Django?

In Django, signals allow certain senders to notify a set of receivers when some action has taken place. You can use built-in signals like pre_save, post_save, etc.

Can you give me an example of using a post_save signal?

Sure! You can create a signal receiver function that listens for the post_save signal of a model. Here's a simple example:

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

@receiver(post_save, sender=MyModel)
def my_model_post_save(sender, instance, created, **kwargs):
    if created:
        print('A new MyModel instance was created!')

What if I want to connect multiple receivers to the same signal?

You can connect multiple receivers to the same signal by defining multiple functions and using the @receiver decorator for each one. Each receiver will be called in the order they were connected.

Are there any performance considerations I should be aware of?

Yes, using signals can introduce performance overhead, especially if you have many receivers or complex logic. It's best to keep signal handlers lightweight and avoid long-running tasks.