silverstripe-subsites/code/model/SubsiteDomain.php

<?php

/**
 * @property text Domain domain name of this subsite. Do not include the URL scheme here
 * @property bool IsPrimary Is this the primary subdomain?
 */
class SubsiteDomain extends DataObject
{
    /**
     *
     * @var array
     */
    private static $db = array(
        "Domain" => "Varchar(255)",
        "IsPrimary" => "Boolean",
    );

    /**
     *
     * @var array
     */
    private static $has_one = array(
        "Subsite" => "Subsite",
    );

    /**
     *
     * @var array
     */
    private static $summary_fields=array(
        'Domain',
        'IsPrimary',
    );

    /**
     * Whenever a Subsite Domain is written, rewrite the hostmap
     *
     * @return void
     */
    public function onAfterWrite()
    {
        Subsite::writeHostMap();
    }
    
    /**
     * 
     * @return \FieldList
     */
    public function getCMSFields()
    {
        $fields = new FieldList(
            new TextField('Domain', $this->fieldLabel('Domain'), null, 255),
            new CheckboxField('IsPrimary', $this->fieldLabel('IsPrimary'))
        );

        $this->extend('updateCMSFields', $fields);
        return $fields;
    }

    /**
     * 
     * @param bool $includerelations
     * @return array
     */
    public function fieldLabels($includerelations = true)
    {
        $labels = parent::fieldLabels($includerelations);
        $labels['Domain'] = _t('SubsiteDomain.DOMAIN', 'Domain');
        $labels['IsPrimary'] = _t('SubsiteDomain.IS_PRIMARY', 'Is Primary Domain');

        return $labels;
    }

    /**
     * Before writing the Subsite Domain, strip out any HTML the user has entered.
     * @return void
     */
    public function onBeforeWrite()
    {
        parent::onBeforeWrite();

        //strip out any HTML to avoid XSS attacks
        $this->Domain = Convert::html2raw($this->Domain);
    }
}