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

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

Django ORM signals are hooks that allow certain senders to notify a set of receivers when some action has taken place. You can use them to execute code in response to events 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, m2m_changed, and pre_delete. Each serves different purposes depending on the action you want to respond to.

How can I connect multiple receivers to a single signal?

You can connect multiple receivers to a single signal by using the @receiver decorator for each function you want to connect. Each receiver will be called in the order they were connected.