Best Practice for Creating a Model's Record in `post_save` Signal While Maintaining Data Integrity in Django

I am working on a Django application where I need to automatically create a Setting record with default values whenever a new User is created. My current implementation uses the post_save signal of the User model to handle this logic.

from django.db.models.signals import post_save
from django.db import transaction
from django.contrib.auth.models import User
from myapp.models import Setting

@receiver(post_save, sender=User)
def create_default_setting(sender, instance, created, **kwargs):
    if created:
        transaction.on_commit(lambda: Setting.objects.create(user=instance))

I used transaction.on_commit to make sure that the creation of the Setting record happens only after the User creation transaction is committed, to avoid issues where the User instance might not yet exist in the database. However, this separates the Setting creation from the User creation transaction. If for any reason the Setting creation fails (e.g., validation errors, database issues), I end up with a User record without a corresponding Setting, which violates data integrity.

On the other hand, if I don't use transaction.on_commit and create the Setting directly in the post_save signal, there is a risk of attempting to create a Setting record before the User instance is fully saved in the database, or creating a Setting even when the User creation fails due to an uncommitted or rolled-back transaction.

This leaves me with two imperfect solutions:

1. Using transaction.on_commit: Ensures the User is committed before the Setting creation but risks incomplete data in case the Setting creation fails.
2. Without transaction.on_commit: Risks trying to create a Setting before the User is fully saved or creating unnecessary Setting records in failed transactions.

My Questions:

1. What is the best practice for handling such scenarios in Django where one model's record depends on the successful creation of another model's record?

2. Is there a way to ensure that the User and Setting records are created within the same transaction to guarantee data integrity while avoiding race conditions or premature queries?

Any guidance or suggestions would be greatly appreciated. Thank you!

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