id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
25488	BaseGenericInlineFormSet runs validation methods before linking form instances to their related object	Ariel Pontes	nobody	"I have a generic inline FormSet class generated like this:

{{{
ProductImageInlineFormset = generic_inlineformset_factory(
    Image, form=ProductImageForm, extra=1)
}}}

and initialized like this:
{{{
product = get_object_or_404(Product.objects.by_id(id))
        image_formset = ProductImageInlineFormset(
            request.POST, request.FILES, instance=product)
}}}

When the individual forms that compose the FormSet are initialized, the ""product"" object is not linked to their instances. This is only done in the BaseGenericInlineFormSet.save_new method:
{{{
def save_new(self, form, commit=True):
    setattr(form.instance, self.ct_field.get_attname(),
        ContentType.objects.get_for_model(self.instance).pk)
    setattr(form.instance, self.ct_fk_field.get_attname(),
        self.instance.pk)
    return form.save(commit=commit)
}}}

This causes problem when the Image class needs to do validation across fields:
{{{
class Image(models.Model):
    ...
    def clean(self):
        related_class = self.content_type.model_class()
        print(self.content_type.model_class())
}}}

The above code results in the following error when trying to save ProductImageInlineFormsets:

{{{
django.db.models.fields.related.RelatedObjectDoesNotExist: Image has no content_type.
}}}

The linking of Image to Product should be done in the form initialization instead. At first sight, after a quick experiment, overriding the `_construct_form` instead of the `save_new` seems to solve the problem:

{{{
 def _construct_form(self, i, **kwargs):
     form = super()._construct_form(i, **kwargs)
     setattr(form.instance, self.ct_field.get_attname(),
         ContentType.objects.get_for_model(self.instance).pk)
     setattr(form.instance, self.ct_fk_field.get_attname(),
         self.instance.pk)
     return form
}}}"	Bug	closed	contrib.contenttypes	1.8	Normal	duplicate	BaseGenericInlineFormSet clean validation		Unreviewed	0	0	0	0	0	0