Set mutation fields explicitly

aleksis/apps/alsijil/schema/documentation.py

@@ -50,7 +50,7 @@ class DocumentationType(PermissionsTypeMixin, DjangoFilterMixin, DjangoObjectTyp
 class DocumentationCreateMutation(DjangoCreateMutation):
     class Meta:
         model = Documentation
-        fields = (
+        only_fields = (
             "course",
             "lesson_event",
             "subject",
@@ -80,7 +80,7 @@ class DocumentationCreateMutation(DjangoCreateMutation):
 class DocumentationBatchCreateMutation(DjangoBatchCreateMutation):
     class Meta:
         model = Documentation
-        fields = (
+        only_fields = (
             "id",
             "course",
             "lesson_event",
@@ -104,7 +104,7 @@ class DocumentationDeleteMutation(DeleteMutation):
 class DocumentationBatchPatchMutation(PermissionBatchPatchMixin, DjangoBatchPatchMutation):
     class Meta:
         model = Documentation
-        fields = (
+        only_fields = (
             "id",
             "course",
             "lesson_event",