Badges: Allow to disable per-product

src/pretix/plugins/badges/forms.py

@@ -1,4 +1,6 @@
 from django import forms
+from django.forms import Field
+from django.forms.models import ModelChoiceIterator
 from django.utils.translation import ugettext_lazy as _
 
 from pretix.plugins.badges.models import BadgeItem, BadgeLayout
@@ -10,10 +12,40 @@ class BadgeLayoutForm(forms.ModelForm):
         fields = ('name',)
 
 
+NoLayoutSingleton = BadgeLayout(pk='-')
+
+
+class BadgeLayoutIterator(ModelChoiceIterator):
+
+    def __iter__(self):
+        yield ("-", _("(Do not print badges)"))
+        yield from super().__iter__()
+
+    def __len__(self):
+        return super().__len__() + 1
+
+
+class BadgeLayoutChoiceField(forms.ModelChoiceField):
+    iterator = BadgeLayoutIterator
+
+    def to_python(self, value):
+        if value == '-':
+            return NoLayoutSingleton
+        return super().to_python(value)
+
+    def validate(self, value):
+        if value == '-':
+            return '-'
+        return Field.validate(self, value)
+
+
 class BadgeItemForm(forms.ModelForm):
+    layout = BadgeLayoutChoiceField(queryset=BadgeLayout.objects.none())
+
     class Meta:
         model = BadgeItem
         fields = ('layout',)
+        exclude = ('layout',)
 
     def __init__(self, *args, **kwargs):
         event = kwargs.pop('event')
@@ -22,6 +54,10 @@ class BadgeItemForm(forms.ModelForm):
         self.fields['layout'].empty_label = _('(Event default)')
         self.fields['layout'].queryset = event.badge_layouts.all()
         self.fields['layout'].required = False
+        if self.instance.pk and not self.instance.layout_id:
+            self.initial['layout'] = NoLayoutSingleton
+        elif self.instance.layout:
+            self.initial['layout'] = self.instance.layout
 
     def save(self, commit=True):
         if self.cleaned_data['layout'] is None:
@@ -29,5 +65,9 @@ class BadgeItemForm(forms.ModelForm):
                 self.instance.delete()
             else:
                 return
+        elif self.cleaned_data['layout'] is NoLayoutSingleton:
+            self.instance.layout = None
+            self.instance.save()
         else:
+            self.instance.layout = self.cleaned_data['layout']
             return super().save(commit=commit)