factory boy - how to generate a subfactory based on condition of a parent attribute

Question

I have a factory like so:

class PayInFactory(factory.DjangoModelFactory):
    class Meta:
        model = PayIn
  
    @factory.lazy_attribute
    def card(self):
        if self.booking_payment and self.booking_payment.payment_type in [bkg_cts.PAYMENT_CARD, bkg_cts.PAYMENT_CARD_2X]:
            factory.SubFactory(
                CardFactory,
                user=self.user,
            )

I'm trying to generate a field card only if the booking_payment field has a payment_type value in [bkg_cts.PAYMENT_CARD, bkg_cts.PAYMENT_CARD_2X]

The code goes into that statement but card field is empty after generation.

How can I do that properly ? Is SubFactory allowed in lazy_attribute ?

I'd like to be able to modify Card field from PayInFactory if possible like so:

>>> PayInFactory(card__user=some_user)

PostGeneration won't do as I need this Card to be available before the call to create. I overrided _create and it may use the card if available.

Thanks !

Answer 1

The solution lies in factory.Maybe:

class PayInFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.PayIn

    card = factory.Maybe(
        factory.LazyAttribute(
            lambda o: o.booking_payment and o.booking_payment.payment_type in ...
        ),
        factory.SubFactory(
            CardFactory,
            # Fetch 'user' one level up from CardFactory: PayInFactory
            user=factory.SelfAttribute('..user'),
        ),
    )

However, I haven't tested whether the extra params get actually passed to the CardFactory, nor what happens when CardFactory is not called — you'll have to check (and maybe open an issue on the project if you get an unexpected behaviour!).