How can I set two primary key fields for my models in Django

Question

I have a model like this:

class Hop(models.Model):     migration = models.ForeignKey('Migration')     host = models.ForeignKey(User, related_name='host_set') 

I want the primary key to be the combination of migration and host.

Answer 1

I would implement this slightly differently.

I would use a default primary key (auto field), and use the meta class property, unique_together

class Hop(models.Model):     migration = models.ForeignKey('Migration')     host = models.ForeignKey(User, related_name='host_set')      class Meta:         unique_together = (("migration", "host"),) 

It would act as a "surrogate" primary key column.

If you really want to create a multi-column primary key, look into this app

Answer 2

Currently, Django models only support a single-column primary key. If you don't specify primary_key = True for the field in your model, Django will automatically create a column id as a primary key.

The attribute unique_together in class Meta is only a constraint for your data.