fix loss of time component in Value(datetime)

Author: timgraham

django_mongodb/expressions.py

@@ -209,6 +209,8 @@ def value(self, compiler, connection):  # noqa: ARG001
         return {"$literal": value}
     if isinstance(value, Decimal):
         return Decimal128(value)
+    if isinstance(value, datetime.datetime):
+        return value
     if isinstance(value, datetime.date):
         # Turn dates into datetimes since BSON doesn't support dates.
         return datetime.datetime.combine(value, datetime.datetime.min.time())

tests/expressions_/test_value.py

@@ -17,7 +17,7 @@ def test_date(self):
     def test_datetime(self):
         self.assertEqual(
             Value(datetime.datetime(2025, 1, 1, 9, 8, 7)).as_mql(None, None),
-            datetime.datetime(2025, 1, 1),
+            datetime.datetime(2025, 1, 1, 9, 8, 7),
         )
 
     def test_decimal(self):