[0.5.X] Fixed #9462 -- Set the instance in an inline formset correctly so that None does not get passed through to the queryset. Thanks tobias and copelco for the ticket.

Backport of r9293 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9294 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/forms/models.py

@@ -446,6 +446,9 @@ class BaseInlineFormSet(BaseModelFormSet):
     def __init__(self, data=None, files=None, instance=None,
                  save_as_new=False, prefix=None):
         from django.db.models.fields.related import RelatedObject
+        if instance is None:
+            self.instance = self.model()
+        else:
             self.instance = instance
         self.save_as_new = save_as_new
         # is there a better way to get the object descriptor?

tests/modeltests/model_formsets/models.py

@@ -107,6 +107,17 @@ class Membership(models.Model):
     date_joined = models.DateTimeField(default=datetime.datetime.now)
     karma = models.IntegerField()
 
+# models for testing a null=True fk to a parent
+class Team(models.Model):
+    name = models.CharField(max_length=100)
+
+class Player(models.Model):
+    team = models.ForeignKey(Team, null=True)
+    name = models.CharField(max_length=100)
+    
+    def __unicode__(self):
+        return self.name
+
 __test__ = {'API_TESTS': """
 
 >>> from datetime import date
@@ -701,4 +712,19 @@ False
 >>> formset.is_valid()
 True
 
+# inlineformset_factory tests with fk having null=True. see #9462.
+# create some data that will exbit the issue
+>>> team = Team.objects.create(name=u"Red Vipers")
+>>> Player(name="Timmy").save()
+>>> Player(name="Bobby", team=team).save()
+
+>>> PlayerInlineFormSet = inlineformset_factory(Team, Player)
+>>> formset = PlayerInlineFormSet()
+>>> formset.get_queryset()
+[]
+
+>>> formset = PlayerInlineFormSet(instance=team)
+>>> formset.get_queryset()
+[<Player: Bobby>]
+
 """}