'The `UniqueFor<Range>Validator` classes always force an implied
\'required\' state on the fields they are applied to.'

def enforce_required_fields(self, attrs):

    missing_items = {field_name: self.missing_message for field_name in [self.field, self.date_field] if (field_name not in attrs)}
    if missing_items:
        raise ValidationError(missing_items, code=u'required')
