Use of _default_manager instead of _base_manager in ForeignKey ModelForm field validation

[ben@…]

I'm not absolutely convinced this is a bug, but it is causing me grief and appears to be a bug when considered against ​Django's documented methodology with respect to "plain" manager usage vs. default manager usage.

The bug I am referring to is located in django/db/models/fields/related.py , line 850, (version 1.3.1)

This is in the "validate" method of ForeignKey. Specifically, the problematic code is:

   qs = self.rel.to.'''_default_manager'''.using(using).filter(
                *''*''{self.rel.field_name: value}
             )
   qs = qs.complex_filter(self.rel.limit_choices_to)
   if not qs.exists():
       raise exceptions.ValidationError(self.error_messages['invalid'] % {
            'model': self.rel.to._meta.verbose_name, 'pk': value}) 
}}

To me, this should be using `_base_manager` instead of `_default_manager` in order to be consistent with Django's stated  plain vs. default "automatic manager" paradigm for foreign key lookups.

The specific problem I am running into is that my default manager's get_queryset method filters out a significant number of records (archived records), but I also have a secondary manager which includes them.  In my form, I have an option to load a ModelChoiceField using the queryset from the secondary manager, including the archived records.  However, validation for my form fails if a archived record is selected, since the above code looks to the default manager (which excludes all archived records) for validation instead of a "plain" manager.

I am looking at creating a custom field in order to override the validate method as a work around, but this seemed like a potential bug to me.  

This is my first bug report, so let me know if other information will be useful.

Ben

[Aymeric Augustin]

Fixed formatting.