public function getById($id, $col = null)
    {
        $id = (int) $id;
        $model = $this->getCacheItem($id);

        if (!$model) {
            $model = $this->getMapper()->getById($id, $col);

            if ($this->useCache) {
                $this->setCacheItem($id, $model);
            }
        }

        return $model;
    }