From 8713ea7568af8871bf1306f14cc928058df0d4c7 Mon Sep 17 00:00:00 2001
From: Josh Smeaton <josh.smeaton@gmail.com>
Date: Wed, 7 Jan 2015 21:30:25 +1100
Subject: [PATCH] Fixed null handling in Value expression

---
 django/db/models/expressions.py |  5 +++++
 tests/annotations/tests.py      |  7 +++++++
 tests/expressions/tests.py      | 15 ++++++++++++++-
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index ac69307edc..9fe3a35fee 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -483,6 +483,11 @@ class Value(ExpressionNode):
         self.value = value
 
     def as_sql(self, compiler, connection):
+        if self.value is None:
+            # cx_Oracle does not always convert None to the appropriate
+            # NULL type (like in case expressions using numbers), so we
+            # use a literal SQL NULL
+            return 'NULL', []
         return '%s', [self.value]
 
 
diff --git a/tests/annotations/tests.py b/tests/annotations/tests.py
index 570ef4d52c..90a9c13048 100644
--- a/tests/annotations/tests.py
+++ b/tests/annotations/tests.py
@@ -190,6 +190,13 @@ class NonAggregateAnnotationTestCase(TestCase):
             lambda d: (d.other_name, d.other_chain, d.is_open, d.book_isbn)
         )
 
+    def test_null_annotation(self):
+        """
+        Test that annotating None onto a model round-trips
+        """
+        book = Book.objects.annotate(no_value=Value(None, output_field=IntegerField())).first()
+        self.assertIsNone(book.no_value)
+
     def test_column_field_ordering(self):
         """
         Test that columns are aligned in the correct order for
diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index 0e9bd57e91..8165a496dc 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -5,7 +5,7 @@ import datetime
 
 from django.core.exceptions import FieldError
 from django.db import connection, transaction, DatabaseError
-from django.db.models import F
+from django.db.models import F, Value
 from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
 from django.test.utils import Approximate
 from django.utils import six
@@ -174,6 +174,19 @@ class BasicExpressionsTests(TestCase):
             ordered=False
         )
 
+    def test_update_with_none(self):
+        Number.objects.create(integer=1, float=1.0)
+        Number.objects.create(integer=2)
+        Number.objects.filter(float__isnull=False).update(float=Value(None))
+        self.assertQuerysetEqual(
+            Number.objects.all(), [
+                None,
+                None,
+            ],
+            lambda n: n.float,
+            ordered=False
+        )
+
     def test_filter_with_join(self):
         # F Expressions can also span joins
         Company.objects.update(point_of_contact=F('ceo'))