How to create instance with new name every time when factory called

Question

I have a factoryboy factory for sqlalchemy model which uses faker

from faker import Faker
from db_init import session

fake = Faker()

class ClientAppFactory(factory.alchemy.SQLAlchemyModelFactory):
    class Meta:
        model = ClientApp
        sqlalchemy_session = session
        sqlalchemy_session_persistence = 'commit'

    name = fake.word()
    display_name = fake.word()

This factory creates rows in database. Field name of my model must be unique. When I call my factory several times in a row, I get several instances with the same name. How can I get different names in my instances?

import pytest
from pytest_factoryboy import register

register(ClientAppFactory)

@pytest.fixture
def several_client_apps():
    ca1 = client_app_factory()
    ca2 = client_app_factory()

In this case I get error about name field unique constraint.

Answer 1

I found an answer. Factory has method build which redefine factory attributes every time when you call it.

@pytest.fixture
def several_client_apps():
    ca1 = client_app_factory.build()
    ca2 = client_app_factory.build()

Answer 2

This is a common mistake with factoryboy and `faker.

Using faker.Faker in a Factory will establish a fixed value on the definition of the class. What you want instead is to use factory.Faker or delay any faker.Faker execution with a lazy function.

An example with both strategies:

from faker import Faker
import factory

fake = Faker()
word_list = ["one", "two", "three"]

class ExampleFactory(factory.DictFactory):

    name = factory.Faker("word")
    display_name = factory.LazyFunction(fake.word)
    another_name = factory.LazyFunction(lambda: fake.word(word_list))

ExampleFactory.bu()
ExampleFactory.create_batch(5)

I used a DictFactory to make it simpler to test, but it should work with model-based factories too.

The another_name field uses a lambda to be able to add parameters to the fake method.