Fixed #2463 -- Fixed temporarily broken many-to-many fields in admin interface…

Fixed #2463 -- Fixed temporarily broken many-to-many fields in admin interface due to [3507]. Thanks, Nesh

git-svn-id: http://code.djangoproject.com/svn/django/trunk@3508 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/__init__.py

@@ -289,8 +289,11 @@ class Field(object):
         if self.choices:
             return first_choice + list(self.choices)
         rel_model = self.rel.to
-        return first_choice + [(getattr(x, self.rel.get_related_field().attname), str(x))
-                               for x in rel_model._default_manager.complex_filter(self.rel.limit_choices_to)]
+        if hasattr(self.rel, 'get_related_field'):
+            lst = [(getattr(x, self.rel.get_related_field().attname), str(x)) for x in rel_model._default_manager.complex_filter(self.rel.limit_choices_to)]
+        else:
+            lst = [(x._get_pk_val(), str(x)) for x in rel_model._default_manager.complex_filter(self.rel.limit_choices_to)]
+        return first_choice + lst
 
     def get_choices_default(self):
         if self.radio_admin: