Fixed #12190 -- Corrected a regression in the ability to instantiate ForeignKeys outside of models. Thanks to jittat for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11730 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/related.py

@@ -695,6 +695,10 @@ class ForeignKey(RelatedField, Field):
             assert isinstance(to, basestring), "%s(%r) is invalid. First parameter to ForeignKey must be either a model, a model name, or the string %r" % (self.__class__.__name__, to, RECURSIVE_RELATIONSHIP_CONSTANT)
         else:
             assert not to._meta.abstract, "%s cannot define a relation with abstract class %s" % (self.__class__.__name__, to._meta.object_name)
+            # For backwards compatibility purposes, we need to *try* and set
+            # the to_field during FK construction. It won't be guaranteed to
+            # be correct until contribute_to_class is called. Refs #12190.
+            to_field = to_field or (to._meta.pk and to._meta.pk.name)
         kwargs['verbose_name'] = kwargs.get('verbose_name', None)
 
         kwargs['rel'] = rel_class(to, to_field,

tests/regressiontests/many_to_one_regress/models.py

@@ -167,4 +167,10 @@ Traceback (most recent call last):
     ...
 ValueError: Cannot assign "<Child: Child object>": "Child.parent" must be a "Parent" instance.
 
+# Regression for #12190 -- Should be able to instantiate a FK
+# outside of a model, and interrogate its related field.
+>>> cat = models.ForeignKey(Category)
+>>> cat.rel.get_related_field().name
+'id'
+
 """}