What are Django model signals and how do I use them?

What are Django model signals and how do I use them?

Django model signals are a way to allow decoupled applications to get notified when certain actions occur elsewhere in the application. They are used to trigger actions automatically when certain events happen, like saving or deleting a model instance.

Can you give me an example of how to use a signal?

Sure! For example, you can use the post_save signal to perform an action right after a model instance is saved. Here's a simple example:

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

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

What other signals are available in Django?

Django provides several built-in signals, including pre_save, post_delete, pre_delete, and m2m_changed. Each of these can be used to hook into different points in the lifecycle of a model instance.

Are there any best practices for using signals?

Yes, some best practices include keeping signal handlers lightweight, avoiding complex logic in them, and being cautious about using them for critical business logic, as they can make the code harder to follow.