What is the role of signals in the Django framework and what are their advantages in application development?

Signals in Django are a mechanism that allows application components to respond to certain events (such as creation, update, or deletion of an object) without tight coupling between them. This implements the observer pattern.

Advantages of signals:

• They allow separating the logic that responds to events from the main business logic.
• They simplify extending functionality without modifying existing code.
• They increase modularity and reusability of code.

For example, you can subscribe to the post_save signal of the User model and automatically create a user profile after registration.

from django.db.models.signals import post_save
from django.dispatch import receiver
from django.contrib.auth.models import User

@receiver(post_save, sender=User)
def create_profile(sender, instance, created, **kwargs):
    if created:
        Profile.objects.create(user=instance)