how to generate unique data in Django using factory and faker?

Question

I am trying to insert data into my database (sqlLite3) using factory and faker.

This is my model:

class User(models.Model):
    id = models.CharField(max_length=9, primary_key=True)
    real_name = models.CharField(max_length=200)
    tz = models.CharField(max_length=200)

Factory for the model:

class UserFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = User

    fake.add_provider(MyProvider)
    real_name = factory.Faker('name')
    id = ''.join(fake.random_letters(length=9)).upper()
    tz = fake.timezone()

When I run UserFactory.create() for the first time, User is added but when I run the second time in the same python shell or try to run UserFactory.create_batch(5), it gives me the following error:

django.db.utils.IntegrityError: UNIQUE constraint failed: activities_user.id

If I run it in a different terminal or exit from shell and run the same command again it runs fine.

Seems ''.join(fake.random_letters(length=9)).upper() always returns same value. Even though I have used random_letters I wonder why this is happening.

I am new to using factory boy and faker. Please help me out on this. Let me know if I am missing anything.

Answer 1

Just found a solution. It was a simple thing! I have modified this line

id = ''.join(fake.random_letters(length=9)).upper()

to

id = factory.Sequence(lambda n: ''.join(fake.random_elements(elements=(string.ascii_uppercase + string.digits), length=9, unique=True)).upper())

and it worked!