protected function doListAll(Elite_Vaf_Model_Level $entity, $parent_id = 0)
 {
     $select = $this->getReadAdapter()->select()->from(array('l' => $entity->getTable()))->order('title')->group('l.title');
     if (is_numeric($parent_id) && $parent_id > 0 && $entity->getPrevLevel()) {
         $select->joinLeft(array('d' => 'elite_definition'), 'l.id = d.' . $entity->getType() . '_id', array())->where('d.' . $entity->getPrevLevel() . '_id = ?', $parent_id);
     }
     if (is_array($parent_id) && $entity->getPrevLevel()) {
         $select->joinLeft(array('d' => 'elite_definition'), 'l.id = d.' . $entity->getType() . '_id', array());
         foreach ($parent_id as $level => $each_parent_id) {
             if (!in_array($level, $this->getSchema()->getLevels(), true)) {
                 throw new Elite_Vaf_Model_Level_Exception_InvalidLevel('Invalid level [' . $level . ']');
             }
             $select->where('d.' . $level . '_id = ?', $each_parent_id);
         }
     }
     $result = $select->query();
     $this->objs[$entity->getType()][$entity->getId()] = array();
     foreach ($result->fetchAll(Zend_Db::FETCH_OBJ) as $row) {
         $obj = $this->find($entity->getType(), $row->id);
         array_push($this->objs[$entity->getType()][$entity->getId()], $obj);
     }
     return $this->objs[$entity->getType()][$entity->getId()];
 }