public function first()
    {
        $data = $this->getData();

        if (!$this->where) {
            return $data
                ? $this->convertItem(reset($data))
                : null;
        }

        foreach ($data as &$rs) {
            if ($this->matchWhere($rs)) {
                return $this->convertItem($rs);
            }
        }

        return null;
    }