Install django-scopes

src/pretix/plugins/pretixdroid/forms.py

@@ -1,6 +1,7 @@
 from django import forms
 from django.urls import reverse
 from django.utils.translation import ugettext_lazy as _
+from django_scopes.forms import SafeModelMultipleChoiceField, SafeModelChoiceField
 
 from pretix.control.forms.widgets import Select2
 from pretix.plugins.pretixdroid.models import AppConfiguration
@@ -16,6 +17,10 @@ class AppConfigurationForm(forms.ModelForm):
             }),
             'app': forms.RadioSelect
         }
+        field_classes = {
+            'items': SafeModelMultipleChoiceField,
+            'list': SafeModelChoiceField,
+        }
 
     def __init__(self, **kwargs):
         self.event = kwargs.pop('event')