fix subject repository build_hash

app/repositories/orient_db/subject_repository.rb

@@ -27,8 +27,8 @@ module OrientDb
       learning_object_repository.build_objects(result)
     end
 
-    def build_hash
-      hash = super
+    def build_hash(object)
+      hash = super(object)
       hash.delete("learning_objects")
       hash
     end