Changed r10668 to not falsely error out when using generic inlines.

The bug was picked up by the tests already, but only if run against a
backend that supports referential integrity.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10732 bcc190cf-cafb-0310-a4f2-bffc1f526a37

1 files changed, 8 insertions, 3 deletions

diff --git a/django/forms/models.py b/django/forms/models.py
index ce75bdcc3b..d42b98483b 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -756,10 +756,13 @@ class BaseInlineFormSet(BaseModelFormSet):
         unique_check = [field for field in unique_check if field != self.fk.name]
         return super(BaseInlineFormSet, self).get_unique_error_message(unique_check)
 
-def _get_foreign_key(parent_model, model, fk_name=None):
+def _get_foreign_key(parent_model, model, fk_name=None, can_fail=False):
     """
-    Finds and returns the ForeignKey from model to parent if there is one.
-    If fk_name is provided, assume it is the name of the ForeignKey field.
+    Finds and returns the ForeignKey from model to parent if there is one
+    (returns None if can_fail is True and no such field exists). If fk_name is
+    provided, assume it is the name of the ForeignKey field. Unles can_fail is
+    True, an exception is raised if there is no ForeignKey from model to
+    parent_model.
     """
     # avoid circular import
     from django.db.models import ForeignKey
@@ -785,6 +788,8 @@ def _get_foreign_key(parent_model, model, fk_name=None):
         if len(fks_to_parent) == 1:
             fk = fks_to_parent[0]
         elif len(fks_to_parent) == 0:
+            if can_fail:
+                return
             raise Exception("%s has no ForeignKey to %s" % (model, parent_model))
         else:
             raise Exception("%s has more than 1 ForeignKey to %s" % (model, parent_model))