BUG#34727432: Fix Django datetime error when USE_TZ=True in settings

oscpache · oscpache · commit 0c589b46bd8a · 2022-11-08T09:30:36.000-06:00
When using the MySQL Connector/Python Django library as the backend in
an application where time zone aware values are set to be used
(USE_TZ=True), the `python migrate.py makemigrations` command fails
with a ValueError exception because at some point Django assumes a
given datetime value is naive and makes it zone aware. However, if the
value is non-naive, an error is raised.

With this patch, the issue is fixed by guaranteeing the
DjangoMySQLConverter class returns naive datetime values.

Change-Id: I9a46331d66b1bc865c4113c2caa0ec4d424abc1a
diff --git a/CHANGES.txt b/CHANGES.txt
@@ -14,6 +14,7 @@ v8.0.32
 - WL#15348: Support MIT Kerberos library on Windows
 - WL#15036: Support for type hints
 - WL#14861: Remove distutils support
+- BUG#34727432: Fix Django datetime error when USE_TZ=True in settings
 - BUG#34710366: Django implementation does not pass unit tests
 - BUG#34695103: Remove debug messages that shows authentication data
 - BUG#34690501: Connector/Python depends on outdated protobuf
diff --git a/lib/mysql/connector/django/base.py b/lib/mysql/connector/django/base.py
@@ -611,20 +611,19 @@ def _datetime_to_python(value: bytes, dsc: Any = None) -> Optional[datetime]:
         """Connector/Python always returns naive datetime.datetime
 
         Connector/Python always returns naive timestamps since MySQL has
-        no time zone support. Since Django needs non-naive, we need to add
-        the UTC time zone.
+        no time zone support.
+
+        - A naive datetime is a datetime that doesn't know its own timezone.
+
+        Django needs a non-naive datetime, but in this method we don't need
+        to make a datetime value time zone aware since Django itself at some
+        point will make it aware (at least in versions 3.2.16 and 4.1.2) when
+        USE_TZ=True. This may change in a future release, we need to keep an
+        eye on this behaviour.
 
         Returns datetime.datetime()
         """
-        if not value:
-            return None
-
-        dt: Optional[datetime] = MySQLConverter._datetime_to_python(value)
-        if dt is None:
-            return None
-        if settings.USE_TZ and timezone.is_naive(dt):
-            dt = dt.replace(tzinfo=timezone.utc)
-        return dt
+        return MySQLConverter._datetime_to_python(value) if value else None
 
     # pylint: enable=unused-argument
 
