How can I set a table constraint “deferrable initially deferred” in django model?

Question

I am trying to set a constraint to a table model in django with a postgresql database.

I can do it via postgresql with this sentence:

ALTER TABLE pub         


        

Answer 1

Very recently, Django has added support for this feature (See ticket). Starting from Django 3.1 you can write:

class UniqueConstraintDeferrable(models.Model):
    name = models.CharField(max_length=255)
    shelf = models.CharField(max_length=31)

    class Meta:
        required_db_features = {
            'supports_deferrable_unique_constraints',
        }
        constraints = [
            models.UniqueConstraint(
                fields=['name'],
                name='name_init_deferred_uniq',
                deferrable=models.Deferrable.DEFERRED,
            ),
            models.UniqueConstraint(
                fields=['shelf'],
                name='sheld_init_immediate_uniq',
                deferrable=models.Deferrable.IMMEDIATE,
            ),
        ]