FactoryBoy creates a new object from SubFactory despite FACTORY_DJANGO_GET_OR_CREATE

I am using the setting FACTORY_DJANGO_GET_OR_CREATE. But in some cases, when I ask for an existing object with an existing SubFactory object, it creates an unused object despite this setting.

For example, in a brand new project, I typed:

# models.py
from django.db import models

class A(models.Model):
    name = models.CharField(max_length=10)

class B(models.Model):
    name = models.CharField(max_length=10)
    a = models.ForeignKey(A)

And

# factories.py
import factory

from . import models

class AFactory(factory.DjangoModelFactory):
    FACTORY_FOR = models.A
    FACTORY_DJANGO_GET_OR_CREATE = ('name',)

    name = factory.Sequence(lambda n: 'A-{0}'.format(n))

class BFactory(factory.DjangoModelFactory):
    FACTORY_FOR = models.B
    FACTORY_DJANGO_GET_OR_CREATE = ('name',)

    name = factory.Sequence(lambda n: 'B-{0}'.format(n))
    a = factory.SubFactory(AFactory)

Then:

from factories import *

a = AFactory(name="Apple")
models.A.objects.all()
# one object
b = BFactory(a__name="Apple", name="Beetle")
models.B.objects.all()
models.A.objects.all()
# one A object, one B object
b = BFactory(name="Beetle")
models.B.objects.all()
models.A.objects.all()
# still one B object, but now a new, unused A object too

The final call to BFactory has brought into being a new object of class A, even though the B object with name Beetle already exists (and is not re-created). Why, and how do I stop this new A object being created?

(I know I can get around this by calling instead:

b = BFactory(name="Beetle", a__name="Apple")

but in my actual use case, I have several dependencies and levels of hierarchy, and it’s messy to supply extra redundant parameters this way - and I can’t seem to get the right combination of parameters.)

Thanks!

(I also asked this on StackOverflow here too.)

[nicolasroma]

Hi @rbarrois! I was working and suddenly I run into this issue. I’m glad that you already know whats going on. I leave here for you 2 questions.

1. Why this error seems to be not idempotent? Debugging the issue I found out that I call the Factory with the same args and some tomes returns the one already created, other times creates a new one and other times it returns an Exception
2. Is there any way to solve this temporally until is fixed?

Thanks in advanced Regards

[daillouf]

Hello everyone,

I’ve just looked at how subfactories are called, and it appeared that any kwargs in the SubFactory call are passed to the factory (the first argument in that call)

So I tried with the following and it works just fine

class BatchFileFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = BatchFile
        django_get_or_create = ('id',)


class RefundFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Refund

    batch_file = factory.SubFactory(BatchFileFactory, id=122)
    amount = 50

And then several calls to RefundFactory all use the same BatchFile with id 122.

Seems like factory-boy also accepts factory.SelfAttribute calls inside those kwargs, like so,

class BatchFileFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = BatchFile
        django_get_or_create = ('id',)


class RefundFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Refund

    batch_file = factory.SubFactory(BatchFileFactory, id=factory.SelfAttribute("..amount"))
    amount = 50

But then “…amount” must be a field on the upper object’s class, here Refund.

Hope this can help