Fixed #12901. Again. Model validation will not be performed on excluded fields...

            # class. See #12901.

            elif self._meta.fields and field not in self._meta.fields:

                exclude.append(f.name)

            elif self._meta.exclude and field in self._meta.exclude:

                exclude.append(f.name)

            # Exclude fields that failed form validation. There's no need for

            # the model fields to validate them as well.

from models import Category

class IncompleteCategoryForm(forms.ModelForm):

class IncompleteCategoryFormWithFields(forms.ModelForm):

    """

    A form that replaces the model's url field with a custom one. This should

    prevent the model field's validation from being called.

        fields = ('name', 'slug')

        model = Category

class IncompleteCategoryFormWithExclude(forms.ModelForm):

    """

    A form that replaces the model's url field with a custom one. This should

    prevent the model field's validation from being called.

    """

    url = forms.CharField(required=False)

    class Meta:

        exclude = ['url']

        model = Category

class ValidationTest(TestCase):

    def test_validates_with_replaced_field(self):

        form = IncompleteCategoryForm(data={'name': 'some name', 'slug': 'some-slug'})

    def test_validates_with_replaced_field_not_specified(self):

        form = IncompleteCategoryFormWithFields(data={'name': 'some name', 'slug': 'some-slug'})

        assert form.is_valid()

    def test_validates_with_replaced_field_excluded(self):

        form = IncompleteCategoryFormWithExclude(data={'name': 'some name', 'slug': 'some-slug'})

        assert form.is_valid()