Fixed #8795: unique_together validation no longer fails on model forms that...

    def validate_unique(self):

        from django.db.models.fields import FieldDoesNotExist

        unique_checks = list(self.instance._meta.unique_together[:])

        # Gather a list of checks to perform. Since this is a ModelForm, some

        # fields may have been excluded; we can't perform a unique check on a

        # form that is missing fields involved in that check.

        unique_checks = []

        for check in self.instance._meta.unique_together[:]:

            fields_on_form = [field for field in check if field in self.fields]

            if len(fields_on_form) == len(check):

                unique_checks.append(check)

        form_errors = []

        # Make sure the unique checks apply to actual fields on the ModelForm

        # Gather a list of checks for fields declared as unique and add them to

        # the list of checks. Again, skip fields not on the form.

        for name, field in self.fields.items():

            try:

                f = self.instance._meta.get_field_by_name(name)[0]

>>> form._errors

{'__all__': [u'Price with this Price and Quantity already exists.']}

>>> class PriceForm(ModelForm):

...     class Meta:

...         model = Price

...         exclude = ('quantity',)

>>> form = PriceForm({'price': '6.00'})

>>> form.is_valid()

True

# Choices on CharField and IntegerField

>>> class ArticleForm(ModelForm):

...     class Meta: