Allow to manually exclude quotas from calendar availability

src/pretix/base/migrations/0190_quota_ignore_for_event_availability.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.3 on 2021-05-27 09:50
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0189_auto_20210525_1311'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='quota',
+            name='ignore_for_event_availability',
+            field=models.BooleanField(default=False),
+        ),
+    ]

src/pretix/base/models/event.py

@@ -260,7 +260,9 @@ class EventMixin:
             Prefetch(
                 'quotas',
                 to_attr='active_quotas',
-                queryset=Quota.objects.using(settings.DATABASE_REPLICA).annotate(
+                queryset=Quota.objects.using(settings.DATABASE_REPLICA).filter(
+                    ignore_for_event_availability=False
+                ).annotate(
                     active_items=Subquery(sq_active_item, output_field=models.TextField()),
                     active_variations=Subquery(sq_active_variation, output_field=models.TextField()),
                 ).exclude(

src/pretix/base/models/items.py

@@ -1517,6 +1517,14 @@ class Quota(LoggedModel):
         verbose_name=_("Variations")
     )
 
+    ignore_for_event_availability = models.BooleanField(
+        verbose_name=_('Ignore this quota when determining event availability'),
+        help_text=_('If you enable this, this quota will be ignored when determining event availability in your event calendar. '
+                    'This is useful e.g. for merchandise that is added to each event but should not stop the event from being shown '
+                    'as sold out.'),
+        default=False,
+    )
+
     close_when_sold_out = models.BooleanField(
         verbose_name=_('Close this quota permanently once it is sold out'),
         help_text=_('If you enable this, when the quota is sold out once, no more tickets will be sold, '