agendas: change on_delete for Agenda -> EventsType to SET_NULL (#85974)

chrono/agendas/migrations/0170_alter_agenda_events_type.py

@@ -0,0 +1,25 @@
+# Generated by Django 3.2.18 on 2024-01-22 10:55
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('agendas', '0169_urlfield_maxlength_increase'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='agenda',
+            name='events_type',
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                related_name='agendas',
+                to='agendas.eventstype',
+                verbose_name='Events type',
+            ),
+        ),
+    ]

chrono/agendas/models.py

@@ -278,7 +278,7 @@ class Agenda(models.Model):
     events_type = models.ForeignKey(
         'agendas.EventsType',
         verbose_name=_('Events type'),
-        on_delete=models.CASCADE,
+        on_delete=models.SET_NULL,
         related_name='agendas',
         null=True,
         blank=True,

tests/manager/test_events_type.py

@@ -162,6 +162,20 @@ def test_delete_events_type(app, admin_user):
     assert EventsType.objects.exists() is False
 
 
+def test_delete_referenced_events_type(app):
+    events_type = EventsType.objects.create(label='Foobar')
+    events_type.save()
+
+    agenda = Agenda(label='Foo Bar', events_type=events_type)
+    agenda.save()
+
+    events_type.delete()
+
+    agenda = Agenda.objects.get(pk=agenda.pk)
+    assert agenda
+    assert agenda.events_type is None
+
+
 def test_delete_events_type_as_manager(app, manager_user):
     agenda = Agenda(label='Foo Bar')
     agenda.view_role = manager_user.groups.all()[0]