protected function max($key, $length)
    {
        $conCate = '';
        $columnName = ucfirst($this->convertToFieldName($key)).' should be ';
        if (isset($this->errors[$key.self::ERROR])) {
            $conCate = str_replace('.', '', $this->errors[$key.self::ERROR]).' and ';
            $columnName = '';
        }

        if (mb_strlen($this->param[$key]) <= $length) {
            $this->errors[$key.self::ERROR] =
                $conCate.$columnName.'maximum '.$length.' characters.';

            return false;
        }

        return true;
    }