protected function buildDataGetterCacheKey()
    {
        $keys = array();

        foreach ($this->columns as $column) {
            if ($column->isPrimaryKey()) {
                $keys[] = '$this->' . $column->getMethodNameGet() . '()';
            }
        }

        $key = "'" . $this->config->getCachePrefix() . "_data_' . " . implode(" . '_' . ", $keys);

        $this->vars['cache_key'] = '
    /**
     * Get cache key
     *
     * @return string
     */
    public function getCacheKey()
    {
        return ' . $key . ';
    }';
    }