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/control/forms/orders.py

@@ -10,7 +10,9 @@ from django.utils.translation import pgettext_lazy, ugettext_lazy as _
 
 from pretix.base.forms import I18nModelForm, PlaceholderValidator
 from pretix.base.forms.widgets import DatePickerWidget
-from pretix.base.models import InvoiceAddress, ItemAddOn, Order, OrderPosition
+from pretix.base.models import (
+    InvoiceAddress, ItemAddOn, Order, OrderPosition, Seat,
+)
 from pretix.base.models.event import SubEvent
 from pretix.base.services.pricing import get_price
 from pretix.control.forms.widgets import Select2
@@ -196,6 +198,12 @@ class OrderPositionAddForm(forms.Form):
         required=False,
         label=_('Add-on to'),
     )
+    seat = forms.ModelChoiceField(
+        Seat.objects.none(),
+        required=False,
+        label=_('Seat'),
+        empty_label=_('General admission')
+    )
     price = forms.DecimalField(
         required=False,
         max_digits=10, decimal_places=2,
@@ -241,6 +249,19 @@ class OrderPositionAddForm(forms.Form):
         else:
             del self.fields['addon_to']
 
+        self.fields['seat'].queryset = order.event.seats.all()
+        self.fields['seat'].widget = Select2(
+            attrs={
+                'data-model-select2': 'seat',
+                'data-select2-url': reverse('control:event.seats.select2', kwargs={
+                    'event': order.event.slug,
+                    'organizer': order.event.organizer.slug,
+                }),
+                'data-placeholder': _('General admission')
+            }
+        )
+        self.fields['seat'].widget.choices = self.fields['seat'].choices
+
         if order.event.has_subevents:
             self.fields['subevent'].queryset = order.event.subevents.all()
             self.fields['subevent'].widget = Select2(
@@ -269,6 +290,11 @@ class OrderPositionChangeForm(forms.Form):
         required=False,
         empty_label=_('(Unchanged)')
     )
+    seat = forms.ModelChoiceField(
+        Seat.objects.none(),
+        required=False,
+        empty_label=_('(Unchanged)')
+    )
     price = forms.DecimalField(
         required=False,
         max_digits=10, decimal_places=2,
@@ -312,6 +338,22 @@ class OrderPositionChangeForm(forms.Form):
         else:
             del self.fields['subevent']
 
+        if instance.seat:
+            self.fields['seat'].queryset = instance.order.event.seats.all()
+            self.fields['seat'].widget = Select2(
+                attrs={
+                    'data-model-select2': 'seat',
+                    'data-select2-url': reverse('control:event.seats.select2', kwargs={
+                        'event': instance.order.event.slug,
+                        'organizer': instance.order.event.organizer.slug,
+                    }),
+                    'data-placeholder': _('(Unchanged)')
+                }
+            )
+            self.fields['seat'].widget.choices = self.fields['seat'].choices
+        else:
+            del self.fields['seat']
+
         choices = [
             ('', _('(Unchanged)'))
         ]