Django IntegrityError 1452

Question

I had an application that was working nicely using a User class that I had defined. After working on this for a few weeks, I realized I needed user authentication, and decided to use django's User class instead (I didn't really understand how this worked when I started, as I'm very new to Django). I got rid of my ForeignKey relation to my custom User class, and added a ForeignKey relation to django.contrib.auth.models.User, however now when I use the Admin page to add a new object, I get:

Exception Type: IntegrityError at /admin/po/purchaseorder/add/
Exception Value: (1452, 'Cannot add or update a child row: a foreign key constraint fails (`po`.`po_purchaseorder`, CONSTRAINT `django_user_id_refs_id_fe5f38af` FOREIGN KEY (`django_user_id`) REFERENCES `auth_user` (`id`))')

I really don't understand this error. Here's the relevant class code:

from django.contrib.auth.models import User

class PurchaseOrder(models.Model):
    user=models.ForeignKey(User)
    request_number = models.AutoField(primary_key=True)
    #More fields 

Can anyone give me any explanation about this error, and why I'm getting it now that I'm using the built in User, as opposed to my own class?

Answer 1

What might had happened is that you updated your models to include the Django's User definition but haven't updated the database yet.

IntegrityErrors mean that some constraint will be violated in the Database if you perform the query. I'm sure that updating the database schema a.k.a python manage.py syncdb will do the trick.

If you are able to drop the schema and created again then that might solve it. If not, just updated the modified tables your models represent.

Hope this helps!