static function getDefinitionTree($definition_id, $parent_id = null) { $nextlevel = new DataDefinitionDetailCollection(new DataDefinitionDetail()); $sh = new SearchHandler($nextlevel, false); $sh->addConstraint(new Constraint('data_definition_id', '=', $definition_id)); if (empty($parent_id)) { $sh->addConstraint(new Constraint('parent_id', 'is', 'NULL')); } else { $sh->addConstraint(new Constraint('parent_id', '=', $parent)); } $sh->setOrderby('position'); $nextlevel->load($sh); return $nextlevel; }