IntegrityError when saving a new model instance

[washougal]

I'm using django-rest-framework, and have a test that requires a specific primary key to be specified from a get request, and another test that takes a post request and saves it. A simplified version of what I have:

#models.py
class Equipment(models.Model):
    equipment_name = models.TextField()

#tests.py
class TestAPI(TestCase):
    def setUp(self):
        self.equipment = mommy.make(
            'App.Equipment',
            equipment_name='Test Equipment',
            id=1
        )

    def test_post(self):
        response = self.client.post(url, {'equipment_name': 'Another piece of equipment'}, format='json')

When setting the primary key in the mommy make method, I get:

IntegrityError: duplicate key value violates unique constraint "App_equipment_pkey" DETAIL: Key (id)=(1) already exists.

Removing the id attribute resolves the problem. Is there a way to explicitly set the primary key for one mommy object, and just rely on django figuring out the primary keys on the next object that's created? Right now I have to split tests into two different classes that could be combined into one.

[berinhard]

@washougal isn't there any lost project's or app's fixture you're defining as initial data? Because the exception being raised (IntegrityError) means the database already has an entry with the id 1. Take a look if there aren't other piece of codes being executed before your test.

About model mommy, it does support id assignment:

In [1]: Dataset.objects.latest('id').id
Out[1]: 6

In [2]: from model_mommy import mommy

In [3]: ds_42 = mommy.make(Dataset, id=42)

In [4]: ds_42.refresh_from_db()

In [5]: ds_42.id
Out[5]: 42