获取 factory_boy 中关联子记录的 id

Question

我有一个function 和多个parameters，然后是该函数的专用instantiation，每个函数的参数都有一些settings。所以我的结构如下：

class Function(models.Model):
    name = models.CharField()

class FunctionParameter(models.Model):
    function = models.ForeignKey(Function)

class FunctionInstantiation(models.Model):
    function = models.ForeignKey(Function)

class ParameterSetting(models.Model):
    function_instantiation = models.ForeignKey(FunctionInstantiation)
    function_parameter = models.ForeignKey(FunctionParameter)

在FunctionFactory 中，我可以使用factory.RelatedFactory 创建parameters。

但是在FunctionInstantiationFactory我不能使用factory.RelatedFactory(ParameterSetting)创建ParameterSettings，因为我无权访问在FunctionFactory中创建的parameter对象，所以我不能设置parameter_setting.function_parameter_id .

FunctionInstantiationFactory 如何查找在FunctionFactory 中创建的参数的parameter_id？我可以从RelatedFactory(FunctionFactory) 的返回值中得到它们吗？还是我需要查看数据库？

Answer 1

factory.SubFactory 旨在关注ForeignKey；如果你想反过来使用它，你应该改用RelatedFactory。

对于你的例子，我会选择以下工厂：

class FunctionFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.Function
    name = factory.Sequence(lambda n: "Function %d" % n)


class FunctionParameterFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.FunctionParameter
    function = factory.SubFactory(FunctionFactory)


class FunctionInstantiationFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.FunctionInstantiation
    function = factory.SubFactory(FunctionFactory)


class ParameterSettingFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.ParameterSetting
        exclude = ['function']

    # We'll need a FunctionFactory; this field is part of 'exclude',
    # thus available while building the factory but not passed to the
    # target Django model
    function = factory.SubFactory(FunctionFactory)

    # Use the function from our Factory for both
    # function_instantiation and function_parameter
    function_instantiation = factory.SubFactory(FunctionInstantiationFactory,
        function=factory.SelfAttribute('..function'))
    function_parameter = factory.SubFactory(FunctionParameterFactory,
        function=factory.SelfAttribute('..function'))

您可以添加一个额外的工厂FunctionWithParametersFactory，它会创建参数：

class FunctionWithParametersFactory(FunctionFactory):
    parameter1 = factory.RelatedFactory(ParameterSettingFactory, 'function')
    parameter2 = factory.RelatedFactory(ParameterSettingFactory, 'function')

调用该工厂将执行以下操作：

1. 创建一个 Function 对象（通过 FunctionFactory）
2. 调用ParameterSettingFactory，将其指向创建的Function对象
3. 再次调用 ParameterSettingFactory，仍然指向同一个 Function 对象
4. 返回该函数对象。

Answer 2

这是 Xelnor 的答案，但修复了错误，以便只创建一个 function_instantiation，而不是为每个 parameter/parameter_setting 对创建一个。

class FunctionFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.Function
    name = factory.Sequence(lambda n: "Function %d" % n)


class FunctionParameterFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.FunctionParameter
    function = factory.SubFactory(FunctionFactory)


class FunctionInstantiationFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.FunctionInstantiation
    function = factory.SubFactory(FunctionFactory)


class ParameterSettingFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.ParameterSetting

    function_instantiation = factory.SubFactory(FunctionInstantiationFactory)
    function_parameter = factory.SubFactory(FunctionParameterFactory,
        function=factory.SelfAttribute('..function_instantiation.function'))


class FunctionToParameterSettingsFactory(FunctionInstantiationFactory):
    class Meta:
        model = models.FunctionInstantiation

    # This overrides the function_instantiation created inside
    # ParameterSettingFactory, which then overrides the Function creation,
    # with the SelfAttribute('..function_instantiation.function') syntax.
    parameter_setting_1 = factory.RelatedFactory(ParameterSettingFactory, 
        'function_instantiation')
    parameter_setting_2 = factory.RelatedFactory(ParameterSettingFactory, 
        'function_instantiation')

以下演示了使用此模式的任何人可能会遇到的其他一些问题的解决方案，例如覆盖相关对象的值，以及到其他表的链接，这些表本身是链接的。它主要来自 Xelnor 在他的回答中介绍的技术。

class FunctionFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.Function
    name = factory.Sequence(lambda n: "Function %d" % n)


class FunctionParameterFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.FunctionParameter
    name = factory.Sequence(lambda n: "Function %d" % n)
    function = factory.SubFactory(FunctionFactory)


class ParameterSettingFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.ParameterSetting
    name = factory.Sequence(lambda n: "Function %d" % n)

    function_instantiation = factory.SubFactory(FunctionInstantiationFactory)
    function_parameter = factory.SubFactory(FunctionParameterFactory,
        function=factory.SelfAttribute('..function_instantiation.function'))


class DatasetAnd2ColumnsFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.Function
    dataset = factory.SubFactory(DatasetFactory,
        name=factory.Sequence(lambda n: "Custom dataset %d" % n))
    column_1 = factory.SubFactory(ColumnFactory, dataset=dataset,
        name=factory.Sequence(lambda n: "Column 1 %d" % n))
    column_2 = factory.SubFactory(ColumnFactory, dataset=dataset,
        name=factory.Sequence(lambda n: "Column 2 %d" % n))


# I found it neater not to inherit in the end, due to needing quite a lot of
# additional complexity not included in my original question.
class FunctionToParameterSettingsFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.FunctionInstantiation

    name = factory.Sequence(lambda n: "Custom instantiation name %d" % n)
    # You can call Sequence to pass values to SubFactories
    function = factory.SubFactory(FunctionFactory, 
        name=factory.Sequence(lambda n: "Custom function %d" % n))

    parameter_setting_1 = factory.RelatedFactory(ParameterSettingFactory, 
        'function_instantiation',
        # Note the __ syntax for override values for nested objects:
        parameter__name='Parameter 1',
        name='Parameter Setting 1')
    # Possible to use Sequence here too, and makes looking at data easier
    parameter_setting_2 = factory.RelatedFactory(ParameterSettingFactory, 
        'function_instantiation',
        parameter__name=factory.Sequence(lambda n: "Param 1 for fn %d" % n),
        name=factory.Sequence(lambda n: "Param Setting 1 for fn %d" % n))

我现在需要创建一个包含一些数据列的数据集，并将参数设置记录与这些列连接起来。为此，请在 FunctionToParameterSettingsFactory 末尾：

@factory.post_generation
def post(self, create, extracted, **kwargs):
    if not create:
         return

    dataset = DatasetAnd2ColumnsFactory()
    column_ids_by_name = 
        dict((column.name, column.id) for column in dataset.column_set.all())

    # self is the `FunctioInstantiation` Django object just created by the `FunctionToParameterSettingsFactory`
    for parameter_setting in self.parametersetting_set.all():
        if parameter_setting.name == 'age_in':
            parameter_setting.column_id = column_ids_by_name['Age']
            parameter_setting.save()
        elif parameter_setting.name == 'income_in':
            parameter_setting.column_id = column_ids_by_name['Income']
            parameter_setting.save()

诚然，这有点 hacky。我尝试在 RelatedFactory 调用中传递column=column_1，但这触发了多个数据集的创建，每一列都链接到不同的数据集。我用 SelfAttribute 和 LazyAttribute 尝试了各种杂技，但是你不能在 RelatedFactory 调用中使用，你不能用 SubFactory(SelfAttribute()) 创建一些东西然后将它传递给 RelatedFactory，因为这会破坏 SelfAttribute（见my other question)。

在我的真实代码中，我还有几个模型具有数据集的外键，它们都绑定得很好。