From 7a0b04fdc3abb8ff4db7ffc81d4a0201f682a82a Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Sun, 12 Mar 2006 04:10:57 +0000
Subject: [PATCH] magic-removal: Modified descriptor to return None rather than
 raising DoesNotExist if null=True for a related field.

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@2511 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/db/models/fields/related.py          |  3 +++
 tests/modeltests/m2o_recursive/models.py    |  6 ++----
 tests/modeltests/many_to_one_null/models.py | 17 +++++++----------
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index d60708496b..2c7bebc759 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -117,6 +117,9 @@ class ReverseSingleRelatedObjectDescriptor(object):
         except AttributeError:
             val = getattr(instance, self.field.attname)
             if val is None:
+                # If Null is an allowed value, return it.
+                if self.field.null:
+                    return None
                 raise self.field.rel.to.DoesNotExist
             other_field = self.field.rel.get_related_field()
             if other_field.rel:
diff --git a/tests/modeltests/m2o_recursive/models.py b/tests/modeltests/m2o_recursive/models.py
index 3c9c4d4b65..e7996bc15f 100644
--- a/tests/modeltests/m2o_recursive/models.py
+++ b/tests/modeltests/m2o_recursive/models.py
@@ -30,10 +30,8 @@ API_TESTS = """
 [Child category]
 >>> r.child_set.get(name__startswith='Child')
 Child category
->>> r.parent
-Traceback (most recent call last):
-    ...
-DoesNotExist
+>>> print r.parent
+None
 
 >>> c.child_set.all()
 []
diff --git a/tests/modeltests/many_to_one_null/models.py b/tests/modeltests/many_to_one_null/models.py
index 8a629aa137..6818493ee3 100644
--- a/tests/modeltests/many_to_one_null/models.py
+++ b/tests/modeltests/many_to_one_null/models.py
@@ -61,23 +61,20 @@ Second
 >>> a3.save()
 >>> a3.id
 3
->>> a3.reporter
-Traceback (most recent call last):
-    ...
-DoesNotExist
+>>> print a3.reporter
+None
 
+# Need to reget a3 to refresh the cache
 >>> a3 = Article.objects.get(pk=3)
 >>> print a3.reporter.id
 Traceback (most recent call last):
     ...
-DoesNotExist
+AttributeError: 'NoneType' object has no attribute 'id'
 
-# Accessing an article's 'reporter' attribute throws ReporterDoesNotExist
+# Accessing an article's 'reporter' attribute returns None
 # if the reporter is set to None.
->>> a3.reporter
-Traceback (most recent call last):
-    ...
-DoesNotExist
+>>> print a3.reporter
+None
 
 # To retrieve the articles with no reporters set, use "reporter__isnull=True".
 >>> Article.objects.filter(reporter__isnull=True)