class Address(models.Model):
    first_line = models.CharField(max_length=50, blank=True)
    second_line = models.CharField(max_length=50, blank=True)
    city = models.CharField(max_length=30, blank=True)
    state = models.CharField(max_length=2, blank=True)
    zipcode = models.CharField(max_length=5, blank=True)
    zipcode_ext = models.CharField(max_length=4, blank=True)

class AddressFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Address

    first_line = "555 Main St."
    second_line = "Unit 2"
    city = "Chicago"
    state = "IL"
    zipcode = "60606"
    zipcode_ext = "1234"

>>> from models import Address
>>> from django.forms.models import modelform_factory
>>> AddressForm = modelform_factory(Address)
>>> from factories import AddressFactory
>>> a = AddressFactory.create()
>>> af = AddressForm(instance = a)
>>> af.is_valid()
False