Fixed #17294 -- Supported nullable DateTimeFields when time zone support is enabled. Thanks pressureman for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17148 bcc190cf-cafb-0310-a4f2-bffc1f526a37

2 files changed, 4 insertions, 1 deletions

diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index 6824ba17f2..04b13aa5c8 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -786,7 +786,7 @@ class DateTimeField(DateField):
 
     def get_prep_value(self, value):
         value = self.to_python(value)
-        if settings.USE_TZ and timezone.is_naive(value):
+        if value is not None and settings.USE_TZ and timezone.is_naive(value):
             # For backwards compatibility, interpret naive datetimes in local
             # time. This won't work during DST change, but we can't do much
             # about it, so we let the exceptions percolate up the call stack.
diff --git a/django/utils/timezone.py b/django/utils/timezone.py
index 16e65fc62d..0476d46f7e 100644
--- a/django/utils/timezone.py
+++ b/django/utils/timezone.py
@@ -228,6 +228,9 @@ def now():
     else:
         return datetime.now()
 
+# By design, these four functions don't perform any checks on their arguments.
+# The caller should ensure that they don't receive an invalid value like None.
+
 def is_aware(value):
     """
     Determines if a given datetime.datetime is aware.