Fixed null handling in Value expression

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]
 
 

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

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'))