Make available languages configurable

src/pretix/control/views/__init__.py

@@ -0,0 +1,28 @@
+from django.views.generic import edit
+
+
+class EventBasedFormMixin:
+
+    def get_form_kwargs(self):
+        kwargs = super().get_form_kwargs()
+        if hasattr(self.request, 'event'):
+            kwargs['event'] = self.request.event
+        return kwargs
+
+
+class CreateView(EventBasedFormMixin, edit.CreateView):
+    """
+    Like Django's default CreateView, but passes the optional event
+    argument to the form. This is necessary for I18nModelForms to work
+    properly.
+    """
+    pass
+
+
+class UpdateView(EventBasedFormMixin, edit.UpdateView):
+    """
+    Like Django's default UpdateView, but passes the optional event
+    argument to the form. This is necessary for I18nModelForms to work
+    properly.
+    """
+    pass