Inheritance for foreign keys

Hi,

I cannot find a way to use the wonderful (it saves my life) InheritanceManager through a ForeignKey. Here’s some code, it will be clearer:

class Product(Model):
    objects = InheritanceManager()

class Shirt(Product):
    …

class Jacket(Product):
    …

class Box(Model):
    product = ForeignKey('Product')

boxes = Box.objects.all()
for box in boxes:
    box.product # How to get shirts and jackets here?

Is there any way to do this? Cannot find it in the doc. If not, that would be a great feature to add.

Regards, Thibault

[renatgalimov]

@rrauenza, thanks for your comment.

I created a simple ForeignKey field which allows my models to return subclassed foreign key values.

class InheritanceForwardManyToOneDescriptor(ForwardManyToOneDescriptor):
    def get_queryset(self, **hints):
        return self.field.remote_field.model.objects.db_manager(hints=hints).select_subclasses()


class InheritanceForeignKey(models.ForeignKey):
    forward_related_accessor_class = InheritanceForwardManyToOneDescriptor

update: It was tested only with Django-2.1/Python-3.6

[itsmealves]

I found a way to do it, so maybe I can help a little bit. First, you need to create a custom manager that always look for the subclasses:

from model_utils.managers import InheritanceManager

class ProductManager(InheritanceManager):
	def get_queryset(self):
		return super(ProductManager, self).get_queryset().select_subclasses()

After that, you plug it into your model and set it as the base manager:

class Product(Model):
	objects = ProductManager()

	class Meta:
		base_manager_name = 'objects'