Django: Enforce multiple field uniqueness on models

Django just keeps getting better and better.

I thought there would be hell to pay with admin form save overriding but it was surprisingly easy.

In the model you wish to enforce uniqueness, simply add a Meta class declaration and give it the property "unique_together".

view sourceprint?

1.class SomeModel(models.Model):

2.  class Meta:

3.    unique_together = (("fieldA", "fieldB"),)

4. 

5.  fieldA = models.ForeignKey(BlahA)

6.  fieldB = models.ForeignKey(BlahB)

7. 

8.  description = models.TextField()

Whalla! Now it will not let you add any rows which would break the "fieldA AND fieldB" uniqueness constraint.

The change is made at a database level so if data already exists you'll have to migrate the changes somehow.

[ Source ]