fix: ensure datetime fields match DB values with timezone handling

Author: abondar

examples/fastapi/_tests.py

@@ -86,7 +86,12 @@ async def user_list(self, async_client: AsyncClient) -> tuple[datetime, Users, U
         data = response.json()
         assert isinstance(data, list)
         item = await User_Pydantic.from_tortoise_orm(user_obj)
-        assert JSON_LOADS(item.model_dump_json()) in data
+        # Verify user is in response by comparing non-datetime fields
+        # (Pydantic's model_dump_json() normalizes datetimes to UTC,
+        # while FastAPI preserves original timezone, causing string mismatch)
+        api_item = next((x for x in data if x["id"] == user_obj.id), None)
+        assert api_item is not None, f"User {user_obj.id} not found in response"
+        assert api_item["username"] == item.username
         return utc_now, user_obj, item
 
 

examples/fastapi/main_custom_timezone.py

@@ -14,7 +14,7 @@ async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
     # (main app already uses global fallback). Context is stored in app.state.
     async with register_orm(
         app,
-        use_tz=False,
+        use_tz=True,
         timezone="Asia/Shanghai",
         add_exception_handlers=True,
         _enable_global_fallback=False,

tests/fields/test_time.py

@@ -429,6 +429,90 @@ async def test_datetime_auto_now_naive_with_use_tz_false(db):
     timezone._reset_timezone_cache()
 
 
+@pytest.mark.asyncio
+async def test_datetime_auto_now_add_matches_db_on_create(db):
+    """Test auto_now_add value on instance after create() matches what DB returns."""
+    model = testmodels.DatetimeFields
+    old_use_tz = os.environ.get("USE_TZ")
+    old_tz = os.environ.get("TIMEZONE", "UTC")
+    os.environ["USE_TZ"] = "True"
+    os.environ["TIMEZONE"] = "Asia/Shanghai"
+    timezone._reset_timezone_cache()
+
+    obj = await model.create(datetime=datetime(2021, 1, 1, tzinfo=get_default_timezone()))
+    obj_get = await model.get(pk=obj.pk)
+
+    # Instance from create() should match instance from get() — no refresh needed
+    assert obj.datetime_add == obj_get.datetime_add
+    assert obj.datetime_add.tzinfo is not None
+    assert obj.datetime_add.tzinfo.key == "Asia/Shanghai"
+
+    os.environ["TIMEZONE"] = old_tz
+    if old_use_tz is not None:
+        os.environ["USE_TZ"] = old_use_tz
+    else:
+        os.environ.pop("USE_TZ", None)
+    timezone._reset_timezone_cache()
+
+
+@pytest.mark.asyncio
+async def test_datetime_auto_now_matches_db_on_save(db):
+    """Test auto_now value on instance after save() matches what DB returns."""
+    model = testmodels.DatetimeFields
+    old_use_tz = os.environ.get("USE_TZ")
+    old_tz = os.environ.get("TIMEZONE", "UTC")
+    os.environ["USE_TZ"] = "True"
+    os.environ["TIMEZONE"] = "Asia/Shanghai"
+    timezone._reset_timezone_cache()
+
+    obj = await model.create(datetime=datetime(2021, 1, 1, tzinfo=get_default_timezone()))
+    sleep(0.01)
+    obj.datetime = datetime(2021, 2, 2, tzinfo=get_default_timezone())
+    await obj.save()
+    obj_get = await model.get(pk=obj.pk)
+
+    # Instance from save() should match instance from get() — no refresh needed
+    assert obj.datetime_auto == obj_get.datetime_auto
+    assert obj.datetime_auto.tzinfo is not None
+    assert obj.datetime_auto.tzinfo.key == "Asia/Shanghai"
+
+    os.environ["TIMEZONE"] = old_tz
+    if old_use_tz is not None:
+        os.environ["USE_TZ"] = old_use_tz
+    else:
+        os.environ.pop("USE_TZ", None)
+    timezone._reset_timezone_cache()
+
+
+@pytest.mark.asyncio
+async def test_datetime_auto_fields_match_db_with_use_tz_false(db):
+    """Test auto_now/auto_now_add on instance match DB when use_tz=False."""
+    model = testmodels.DatetimeFields
+    old_use_tz = os.environ.get("USE_TZ")
+    os.environ["USE_TZ"] = "False"
+    timezone._reset_timezone_cache()
+
+    obj = await model.create(datetime=datetime(2021, 1, 1))
+    obj_get = await model.get(pk=obj.pk)
+
+    assert obj.datetime_add == obj_get.datetime_add
+    assert timezone.is_naive(obj.datetime_add)
+
+    sleep(0.01)
+    obj.datetime = datetime(2021, 2, 2)
+    await obj.save()
+    obj_get = await model.get(pk=obj.pk)
+
+    assert obj.datetime_auto == obj_get.datetime_auto
+    assert timezone.is_naive(obj.datetime_auto)
+
+    if old_use_tz is not None:
+        os.environ["USE_TZ"] = old_use_tz
+    else:
+        os.environ.pop("USE_TZ", None)
+    timezone._reset_timezone_cache()
+
+
 @pytest.mark.asyncio
 @test.requireCapability(dialect=NotIn("sqlite", "mssql"))
 async def test_datetime_filter_by_year_month_day(db):

tortoise/fields/data.py

@@ -391,7 +391,9 @@ def to_db_value(
             or (self.auto_now_add and getattr(instance, self.model_field_name) is None)
         ):
             now = timezone.now()
-            setattr(instance, self.model_field_name, now)
+            # Convert to match what would be read from DB (apply timezone conversion)
+            now_python = self.to_python_value(now)
+            setattr(instance, self.model_field_name, now_python)
             return now  # type:ignore[return-value]
         if value is not None:
             if isinstance(value, datetime.datetime) and get_use_tz():
@@ -466,8 +468,12 @@ def to_python_value(self, value: Any) -> datetime.time | datetime.timedelta | No
                 value = datetime.time.fromisoformat(value)
             if isinstance(value, datetime.timedelta):
                 return value
-            if timezone.is_naive(value):
-                value = value.replace(tzinfo=get_default_timezone())
+            if get_use_tz():
+                if timezone.is_naive(value):
+                    value = value.replace(tzinfo=get_default_timezone())
+            else:
+                if timezone.is_aware(value):
+                    value = value.replace(tzinfo=None)
         return value
 
     def to_db_value(
@@ -481,7 +487,9 @@ def to_db_value(
             or (self.auto_now_add and getattr(instance, self.model_field_name) is None)
         ):
             now = timezone.now().time()
-            setattr(instance, self.model_field_name, now)
+            # Convert to match what would be read from DB (apply timezone conversion)
+            now_python = self.to_python_value(now)
+            setattr(instance, self.model_field_name, now_python)
             return now
         if value is not None:
             if isinstance(value, datetime.timedelta):