In Factory Boy, how to join strings created with Faker?

Question

I want to use Factory Boy and its support for Faker to generate strings from more than one provider. e.g. combining prefix and name:

# models.py
from django.db import models

class Person(models.Model):
    full_name = models.CharField(max_length=255, blank=False, null=False)


# factories.py
import factory

class PersonFactory(factory.Factory):
    class Meta:
        model = models.Person

    full_name = '{} {}'.format(factory.Faker('prefix'), factory.Faker('name'))

But this doesn't seem to work. e.g.:

>>> person = PersonFactory()
>>> person.full_name
'<factory.faker.Faker object at 0x7f25f4b09e10> <factory.faker.Faker object at 0x7f25f4ab74d0>'

What am I missing?

Antlion

What are the fields on your models.Person class? This is relevant info. – Aixlachapelle

OK, I wasn't sure it would help, but I've added it now. – Antlion

@PhilGyford: Does this work? You'd have to create a prefix and a name class attribute that don't exist in your model and then combine them to create full_name. I'm not sure if this will cause an error, as your original Person model doesn't have those fields. – Microfilm

@Microfilm Thanks, but I tried that, and did get an error for the reason you suggest. – Antlion

Answer 1

You can use the (essentially undocumented) exclude attribute to make your first approach work:

class PersonFactory(factory.Factory):
    class Meta:
        model = Person
        exclude = ('prefix', 'name')

    # Excluded
    prefix = factory.Faker('prefix')
    name = factory.Faker('name')

    # Shows up
    full_name = factory.LazyAttribute(lambda p: '{} {}'.format(p.prefix, p.name))

You could also just use factory.LazyAttribute and generate it all in one go by directly using faker:

from faker import Faker

fake = Faker()

class PersonFactory(factory.Factory):
    class Meta:
        model = Person

    # Shows up
    full_name = factory.LazyAttribute(lambda p: '{} {}'.format(fake.prefix(), fake.name()))

The downside of this approach is that you you don't have easy access to the person's prefix or name.

Microfilm

Thanks! I thought maybe there was a way with factory.LazyAttribute but never managed to find quite the right combination of fakes. – Antlion

Pretty good. Only quibble is that you will generate transgender (in the literal sense of the word) names this way. – Aixlachapelle