Allow to use custom domains for some but not all events (Z#23153875) (#4627)

* Allow to use custom domains for some but not all events

* Update src/pretix/multidomain/urlreverse.py

* Apply suggestions from code review

Co-authored-by: Mira <weller@rami.io>

* Logging for domain config changes

---------

Co-authored-by: Mira <weller@rami.io>

src/pretix/multidomain/migrations/0003_alternativedomainassignment_knowndomain_mode_and_more.py

@@ -0,0 +1,71 @@
+# Generated by Django 4.2.16 on 2024-11-12 10:46
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("pretixbase", "0273_remove_checkinlist_auto_checkin_sales_channels"),
+        ("pretixmultidomain", "0002_knowndomain_event"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="AlternativeDomainAssignment",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        auto_created=True, primary_key=True, serialize=False
+                    ),
+                ),
+            ],
+        ),
+        migrations.AddField(
+            model_name="knowndomain",
+            name="mode",
+            field=models.CharField(default="organizer", max_length=255),
+        ),
+        migrations.AlterField(
+            model_name="knowndomain",
+            name="event",
+            field=models.OneToOneField(
+                null=True,
+                on_delete=django.db.models.deletion.PROTECT,
+                related_name="domain",
+                to="pretixbase.event",
+            ),
+        ),
+        migrations.RunSQL(
+            sql="UPDATE pretixmultidomain_knowndomain SET mode = 'event' WHERE event_id IS NOT NULL",
+            reverse_sql=migrations.RunSQL.noop,
+        ),
+        migrations.AddConstraint(
+            model_name="knowndomain",
+            constraint=models.UniqueConstraint(
+                condition=models.Q(("mode", "organizer")),
+                fields=("organizer",),
+                name="unique_organizer_domain",
+            ),
+        ),
+        migrations.AddField(
+            model_name="alternativedomainassignment",
+            name="domain",
+            field=models.ForeignKey(
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="event_assignments",
+                to="pretixmultidomain.knowndomain",
+            ),
+        ),
+        migrations.AddField(
+            model_name="alternativedomainassignment",
+            name="event",
+            field=models.OneToOneField(
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="alternative_domain_assignment",
+                to="pretixbase.event",
+            ),
+        ),
+    ]