Hotfix for exporters via API (#6007)

* Hotfix for exporters via API

* Apply suggestion from @raphaelm

src/pretix/api/serializers/exporters.py

@@ -75,7 +75,8 @@ class JobRunSerializer(serializers.Serializer):
     def to_representation(self, instance):
         # Translate between events as a list of slugs (API) and list of ints (database)
         if self.ex.is_multievent and not isinstance(self.ex, OrganizerLevelExportMixin) and "events" in instance and isinstance(instance["events"], list):
-            instance["events"] = [e.slug for e in self.ex.events.filter(pk__in=instance["events"]).only("slug")]
+            instance["events"] = [e for e in self.ex.events.filter(pk__in=instance["events"])]
+        instance = super().to_representation(instance)
         return instance
 
     def to_internal_value(self, data):

src/pretix/api/serializers/forms.py

@@ -65,8 +65,9 @@ def form_field_to_serializer_field(field):
         if isinstance(field, m_from):
             return m_to(
                 required=field.required,
-                allow_null=not field.required,
+                allow_null=not field.required and not isinstance(field, forms.BooleanField),
                 validators=field.validators,
+                initial=field.initial,
                 **{kwarg: getattr(field, kwarg, None) for kwarg in m_kwargs}
             )