diff -r 5ff1fc726848 -r c6bca38c1cbf parts/django/tests/regressiontests/null_fk/models.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/parts/django/tests/regressiontests/null_fk/models.py	Sat Jan 08 11:20:57 2011 +0530
@@ -0,0 +1,33 @@
+"""
+Regression tests for proper working of ForeignKey(null=True).
+"""
+
+from django.db import models
+
+class SystemDetails(models.Model):
+    details = models.TextField()
+
+class SystemInfo(models.Model):
+    system_details = models.ForeignKey(SystemDetails)
+    system_name = models.CharField(max_length=32)
+
+class Forum(models.Model):
+    system_info = models.ForeignKey(SystemInfo)
+    forum_name = models.CharField(max_length=32)
+
+class Post(models.Model):
+    forum = models.ForeignKey(Forum, null=True)
+    title = models.CharField(max_length=32)
+
+    def __unicode__(self):
+        return self.title
+
+class Comment(models.Model):
+    post = models.ForeignKey(Post, null=True)
+    comment_text = models.CharField(max_length=250)
+
+    class Meta:
+        ordering = ('comment_text',)
+
+    def __unicode__(self):
+        return self.comment_text