Create OneToOne instance on model creation

Question

I\'m building my first django app. I have a user, and the user has a list of favourites. A user has exactly one list of favourites, and that list belongs exclusively to that

Answer 1

The most common way to accomplish this is to use the Django signals system. You can attach a signal handler (just a function somewhere) to the post_save signal for the User model, and create your favorites list inside of that callback.

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_favorites(sender, instance, created, **kwargs):
    if created:
        Favorites.objects.create(user=instance)

The above was adapted from the Django signals docs. Be sure to read the signals docs entirely because there are a few issues that can snag you such as where your signal handler code should live and how to avoid duplicate handlers.

Answer 2

One way would be to register a post_save signal with next handler:

def user_save(sender, instance, created, **kwargs):
  if created:
     FavouriteList.objects.get_or_create(user=instance)

Answer 3

An excellent django-annoying plugin solves this for you with AutoOneToOneField. I'm using it for user profiles in all django projects I work on.