Add support for reserved seating (#1228)

* Initial work on seating

* Add seat guids

* Add product_list_top

* CartAdd: Ignore item when a seat is passed

* Cart display

* product_list_top → render_seating_plan

* Render seating plan in voucher redemption

* Fix failing tests

* Add tests for extending cart positions with seats

* Add subevent_forms to docs

* Update schema, migrations

* Dealing with expired orders

* steps to order change

* Change order positions

* Allow to add seats

* tests for ocm

* Fix things after rebase

* Seating plans API

* Add more tests for cart behaviour

* Widget support

* Adjust widget tests

* Re-enable CSP

* Update schema

* Api: position.seat

* Add guid to word list

* API: (sub)event.seating_plan

* Vali fixes

* Fix api

* Fix reference in test

* Fix test for real

src/pretix/api/serializers/organizer.py

@@ -1,8 +1,20 @@
 from pretix.api.serializers.i18n import I18nAwareModelSerializer
-from pretix.base.models import Organizer
+from pretix.api.serializers.order import CompatibleJSONField
+from pretix.base.models import Organizer, SeatingPlan
+from pretix.base.models.seating import SeatingPlanLayoutValidator
 
 
 class OrganizerSerializer(I18nAwareModelSerializer):
     class Meta:
         model = Organizer
         fields = ('name', 'slug')
+
+
+class SeatingPlanSerializer(I18nAwareModelSerializer):
+    layout = CompatibleJSONField(
+        validators=[SeatingPlanLayoutValidator()]
+    )
+
+    class Meta:
+        model = SeatingPlan
+        fields = ('id', 'name', 'layout')