View file upload/src/addons/XenCentral/Feedback/Option/Validate.php

<?php
/**
 * @package XenCentral Feedback System
 * @author DNF Technology
 * @copyright Drnoyan & Nalyan LDA, Portugal, EU
 * @license http://dnf.technology/terms/
 * @link http://customers.dnf.technology
 * @version 2.0.0 Beta 10
 * @revision 12
 */

namespace XenCentral\Feedback\Option;

use  XF\Option\AbstractOption;

class Validate extends AbstractOption
{

    public static function validatePrefix(&$value, \XF\Entity\Option $option)

    {

        if (!preg_match('#^[a-zA-Z][a-zA-Z0-9]*$#', $value))
        {
            $option->error(\XF::phrase('xcfs_please_enter_valid_prefix'), $option->option_id);
            return false;
        }

        return true;
    }

}