fix deleting schedules

django_toosimple_q/admin.py

@@ -188,6 +188,10 @@ def last_due_(self, obj):
 
     @admin.display()
     def next_due_(self, obj):
+        # for schedule not in the code anymore
+        if not obj.schedule:
+            return "invalid"
+
         if len(obj.past_dues) >= 1:
             next_due = obj.past_dues[0]
         else:

django_toosimple_q/models.py

@@ -204,6 +204,10 @@ def icon(self):
 
     @cached_property
     def past_dues(self):
+        if self.schedule is None:
+            # Deal with invalid schedule (e.g. deleted from the code but still in the DB)
+            return []
+
         if self.schedule.cron == "manual":
             # A manual schedule is never due
             return []

django_toosimple_q/tests/tests_regression.py

@@ -1,11 +1,15 @@
 import time
 
+from django.core import management
+
+from django_toosimple_q.decorators import register_task, schedule_task
 from django_toosimple_q.models import TaskExec
+from django_toosimple_q.registry import schedules_registry, tasks_registry
 
-from .base import TooSimpleQBackgroundTestCase
+from .base import TooSimpleQBackgroundTestCase, TooSimpleQRegularTestCase
 
 
-class TestRegression(TooSimpleQBackgroundTestCase):
+class TestRegressionBackground(TooSimpleQBackgroundTestCase):
     def test_regr_schedule_short(self):
         # Regression test for an issue where a schedule with smaller periods was not always processed
 
@@ -17,3 +21,22 @@ def test_regr_schedule_short(self):
 
         # It should do almost 20 tasks
         self.assertGreaterEqual(TaskExec.objects.all().count(), 18)
+
+
+class TestRegressionRegular(TooSimpleQRegularTestCase):
+    def test_deleting_schedule(self):
+        # Regression test for an issue where deleting a schedule in code would crash the admin view
+
+        @schedule_task(cron="0 12 * * *", datetime_kwarg="scheduled_on")
+        @register_task(name="normal")
+        def a(scheduled_on):
+            return f"{scheduled_on:%Y-%m-%d %H:%M}"
+
+        management.call_command("worker", "--until_done")
+
+        schedules_registry.clear()
+        tasks_registry.clear()
+
+        # the admin view still works even for deleted schedules
+        response = self.client.get("/admin/toosimpleq/scheduleexec/")
+        self.assertEqual(response.status_code, 200)