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djangodjango-modelsdjango-south

South Auto-migrate Adding Erroneous Unique Constraint

I've got the following bit of code in one of my models:

channel = models.OneToOneField(Channel, related_name='stories', null=True, blank=True, unique=False)

See the unique=False? Well, when I use south to create an auto migration, it wants to add a unique constraint:

./manage.py schemamigration core --auto
 ~ Changed field channel on core.Story
 + Added unique constraint for ['channel'] on core.Story

What gives!?

Solution

  • This is Django, not South. Being unique is built into the definition of OneToOneField. (You can see it in the source code here.)

    If unique is False then there can be more than one Story with the same Channel. This is a ManyToOne relationship, so you probably want this to be a ForeignKey field instead.