essential_admin_setting_configselect.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Config select setting that sets the default on first run.  Proof of concept before tracker issue.
 *
 * @package    theme
 * @subpackage essential
 * @copyright  &copy; 2016-onwards G J Barnard.
 * @author     G J Barnard - {@link http://moodle.org/user/profile.php?id=442195}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die;

class essential_admin_setting_configselect extends admin_setting_configselect {
    /**
     * Returns XHTML select field
     *
     * Ensure the options are loaded, and generate the XHTML for the select
     * element and any warning message. Separating this out from output_html
     * makes it easier to subclass this class.
     *
     * @param string $data the option to show as selected.
     * @param string $current the currently selected option in the database, null if none.
     * @param string $default the default selected option.
     * @return array the HTML for the select element, and a warning message.
     */
    public function output_select_html($data, $current, $default, $extraname = '') {
        if (!$this->load_choices() or empty($this->choices)) {
            return array('', '');
        }

        if (is_null($current)) {
            // First run.
            if ((!is_null($default)) and (empty($data))) {
                $data = $default;
            }
        }

        return parent::output_select_html($data, $current, $default, $extraname);
    }
}