fix get unique timezones

django_celery_beat/schedulers.py

@@ -1,4 +1,6 @@
 """Beat Scheduler Implementation."""
+from __future__ import annotations
+
 import datetime
 import logging
 import math
@@ -15,7 +17,7 @@
 from celery.utils.time import maybe_make_aware
 from django.conf import settings
 from django.core.exceptions import ObjectDoesNotExist
-from django.db import close_old_connections, transaction
+from django.db import close_old_connections, connection, transaction
 from django.db.models import Case, F, IntegerField, Q, When
 from django.db.models.functions import Cast
 from django.db.utils import DatabaseError, InterfaceError
@@ -330,14 +332,14 @@
                 # Handle each timezone specifically
                 *[
                     When(
-                        timezone=timezone_name,
+                        timezone=timezone,
                         then=(
                             F('hour_int')
-                            + self._get_timezone_offset(timezone_name)
+                            + self._get_timezone_offset(timezone)
                             + 24
                         ) % 24
                     )
-                    for timezone_name in self._get_unique_timezone_names()
+                    for timezone in self._get_unique_timezones()
                 ],
                 # Default case - use hour as is
                 default=F('hour_int')
@@ -365,13 +367,27 @@
             f"{hour:02d}" for hour in range(10)
         ]
 
-    def _get_unique_timezone_names(self):
-        """Get a list of all unique timezone names used in CrontabSchedule"""
-        return CrontabSchedule.objects.values_list(
-            'timezone', flat=True
-        ).distinct()
+    def _get_unique_timezones(self) -> set[ZoneInfo]:
+        """Get a set of all unique timezones used in CrontabSchedule"""
+        # sqlite does not support distinct on a column
+        if connection.vendor == 'sqlite':
+            return set(
+                CrontabSchedule.objects.values_list(
+                    'timezone', flat=True
+                )
+            )
+
+        return set(
+            CrontabSchedule.objects.order_by(
+                'timezone'
+            ).distinct(
+                'timezone'
+            ).values_list(
+                'timezone', flat=True
+            )
+        )
 
-    def _get_timezone_offset(self, timezone_name):
+    def _get_timezone_offset(self, timezone: ZoneInfo) -> int:
         """
         Args:
             timezone_name: The name of the timezone or a ZoneInfo object
@@ -387,17 +403,12 @@
         else:
             server_tz = ZoneInfo(str(server_time.tzinfo))
 
-        if isinstance(timezone_name, ZoneInfo):
-            timezone_name = timezone_name.key
-
-        target_tz = ZoneInfo(timezone_name)
-
         # Use a fixed point in time for the calculation to avoid DST issues
         fixed_dt = datetime.datetime(2023, 1, 1, 12, 0, 0)
 
         # Calculate the offset
         dt1 = fixed_dt.replace(tzinfo=server_tz)
-        dt2 = fixed_dt.replace(tzinfo=target_tz)
+        dt2 = fixed_dt.replace(tzinfo=timezone)
 
         # Calculate hour difference
         offset_seconds = (

t/unit/test_schedulers.py

@@ -333,7 +333,7 @@ def test_entry_is_due__no_use_tz(self):
         assert self.app.timezone.key == 'Europe/Berlin'
 
         # simulate last_run_at from DB - not TZ aware but localtime
-        right_now = datetime.utcnow()
+        right_now = datetime.now(dt_timezone.utc)
 
         m = self.create_model_crontab(
             crontab(minute='*/10'),
@@ -364,7 +364,7 @@ def test_entry_and_model_last_run_at_with_utc_no_use_tz(self, monkeypatch):
             time.tzset()
         assert self.app.timezone.key == 'Europe/Berlin'
         # simulate last_run_at from DB - not TZ aware but localtime
-        right_now = datetime.utcnow()
+        right_now = datetime.now(dt_timezone.utc)
         # make sure to use fixed date time
         monkeypatch.setattr(self.Entry, '_default_now', lambda o: right_now)
         m = self.create_model_crontab(
@@ -398,7 +398,7 @@ def test_entry_and_model_last_run_at_when_model_changed(self, monkeypatch):
             time.tzset()
         assert self.app.timezone.key == 'Europe/Berlin'
         # simulate last_run_at from DB - not TZ aware but localtime
-        right_now = datetime.utcnow()
+        right_now = datetime.now(dt_timezone.utc)
         # make sure to use fixed date time
         monkeypatch.setattr(self.Entry, '_default_now', lambda o: right_now)
         m = self.create_model_crontab(
@@ -451,7 +451,7 @@ def test_entry_is_due__celery_timezone_doesnt_match_time_zone(self):
 
         # simulate last_run_at all none, doing the same thing that
         # _default_now() would do
-        right_now = datetime.utcnow()
+        right_now = datetime.now(dt_timezone.utc)
 
         m = self.create_model_crontab(
             crontab(minute='*/10'),
@@ -1224,6 +1224,21 @@ def test_crontab_special_hour_four(self):
         # The hour=4 task should never be excluded
         assert task_hour_four.id not in excluded_tasks
 
+    @pytest.mark.django_db
+    def test_get_unique_timezones(self):
+        """
+        Test that get unique timezones returns a list of unique timezones
+        """
+        # Create 2 crontabs with same timezone, and 1 with different timezone
+        CrontabSchedule.objects.create(hour='4', timezone='UTC')
+        CrontabSchedule.objects.create(hour='4', timezone='UTC')
+        CrontabSchedule.objects.create(hour='4', timezone='America/New_York')
+
+        timezones = self.s._get_unique_timezones()
+
+        assert len(timezones) == 2
+        assert set(timezones) == {ZoneInfo('UTC'), ZoneInfo('America/New_York')}
+
     @pytest.mark.django_db
     @patch('django_celery_beat.schedulers.aware_now')
     @patch('django.utils.timezone.get_current_timezone')
@@ -1663,31 +1678,6 @@ def setup_method(self):
     def teardown_method(self):
         patch.stopall()
 
-    @patch("django_celery_beat.schedulers.aware_now")
-    def test_server_timezone_handling_with_zoneinfo(self, mock_aware_now):
-        """Test handling when server timezone
-        is already a ZoneInfo instance."""
-
-        # Create a mock scheduler with only the methods we need to test
-        class MockScheduler:
-            _get_timezone_offset = (
-                schedulers.DatabaseScheduler._get_timezone_offset
-            )
-
-        s = MockScheduler()
-
-        tokyo_tz = ZoneInfo("Asia/Tokyo")
-        mock_now = datetime(2023, 1, 1, 12, 0, 0, tzinfo=tokyo_tz)
-        mock_aware_now.return_value = mock_now
-
-        # Test with a different timezone
-        new_york_tz = "America/New_York"
-        offset = s._get_timezone_offset(new_york_tz)  # Pass self explicitly
-
-        # Tokyo is UTC+9, New York is UTC-5, so difference should be 14 hours
-        assert offset == 14
-        assert mock_aware_now.called
-
     @patch("django_celery_beat.schedulers.aware_now")
     def test_timezone_offset_with_zoneinfo_object_param(self, mock_aware_now):
         """Test handling when timezone_name parameter is a ZoneInfo object."""
@@ -1709,3 +1699,4 @@ class MockScheduler:
 
         # Tokyo is UTC+9, New York is UTC-5, so difference should be 14 hours
         assert offset == 14
+        assert mock_aware_now.called