Solve cart deletion issues once and for all

src/pretix/api/views/event.py

@@ -272,6 +272,8 @@ class SubEventViewSet(ConditionalListView, viewsets.ModelViewSet):
                     auth=self.request.auth,
                     data=self.request.data
                 )
+                instance.cartposition_set.filter(addon_to__isnull=False).delete()
+                instance.cartposition_set.all().delete()
                 super().perform_destroy(instance)
         except ProtectedError:
             raise PermissionDenied('The sub-event could not be deleted as some constraints (e.g. data created by '

src/pretix/api/views/item.py

@@ -84,6 +84,7 @@ class ItemViewSet(ConditionalListView, viewsets.ModelViewSet):
             user=self.request.user,
             auth=self.request.auth,
         )
+        self.get_object().cartposition_set.filter(addon_to__isnull=False).delete()
         self.get_object().cartposition_set.all().delete()
         super().perform_destroy(instance)
 

src/pretix/api/views/voucher.py

@@ -111,7 +111,10 @@ class VoucherViewSet(viewsets.ModelViewSet):
             user=self.request.user,
             auth=self.request.auth,
         )
-        super().perform_destroy(instance)
+        with transaction.atomic():
+            instance.cartposition_set.filter(addon_to__isnull=False).delete()
+            instance.cartposition_set.all().delete()
+            super().perform_destroy(instance)
 
     @list_route(methods=['POST'])
     def batch_create(self, request, *args, **kwargs):

src/pretix/base/models/event.py

@@ -759,6 +759,7 @@ class Event(EventMixin, LoggedModel):
         return not self.orders.exists() and not self.invoices.exists()
 
     def delete_sub_objects(self):
+        self.cartposition_set.filter(addon_to__isnull=False).delete()
         self.cartposition_set.all().delete()
         self.items.all().delete()
         self.subevents.all().delete()

src/pretix/control/views/item.py

@@ -1158,6 +1158,7 @@ class ItemDelete(EventPermissionRequiredMixin, DeleteView):
         success_url = self.get_success_url()
         o = self.get_object()
         if o.allow_delete():
+            self.get_object().cartposition_set.filter(addon_to__isnull=False).delete()
             self.get_object().cartposition_set.all().delete()
             self.get_object().log_action('pretix.event.item.deleted', user=self.request.user)
             self.get_object().delete()

src/pretix/control/views/subevents.py

@@ -117,6 +117,7 @@ class SubEventDelete(EventPermissionRequiredMixin, DeleteView):
             return HttpResponseRedirect(self.get_success_url())
         else:
             self.object.log_action('pretix.subevent.deleted', user=self.request.user)
+            self.object.cartposition_set.filter(addon_to__isnull=False).delete()
             self.object.cartposition_set.all().delete()
             self.object.delete()
             messages.success(request, pgettext_lazy('subevent', 'The selected date has been deleted.'))
@@ -512,6 +513,7 @@ class SubEventBulkAction(EventPermissionRequiredMixin, View):
         elif request.POST.get('action') == 'delete_confirm':
             for obj in self.objects:
                 if obj.allow_delete():
+                    obj.cartposition_set.filter(addon_to__isnull=False).delete()
                     obj.cartposition_set.all().delete()
                     obj.log_action('pretix.subevent.deleted', user=self.request.user)
                     obj.delete()

src/pretix/control/views/vouchers.py

@@ -143,6 +143,7 @@ class VoucherDelete(EventPermissionRequiredMixin, DeleteView):
             messages.error(request, _('A voucher can not be deleted if it already has been redeemed.'))
         else:
             self.object.log_action('pretix.voucher.deleted', user=self.request.user)
+            self.object.cartposition_set.filter(addon_to__isnull=False).delete()
             self.object.cartposition_set.all().delete()
             self.object.delete()
             messages.success(request, _('The selected voucher has been deleted.'))
@@ -348,6 +349,7 @@ class VoucherBulkAction(EventPermissionRequiredMixin, View):
             for obj in self.objects:
                 if obj.allow_delete():
                     obj.log_action('pretix.voucher.deleted', user=self.request.user)
+                    obj.cartposition_set.filter(addon_to__isnull=False).delete()
                     obj.cartposition_set.all().delete()
                     obj.delete()
                 else: