DisallowRobotsIndexingListener.php

<?php


/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Symfony\Component\HttpKernel\EventListener;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\Event\ResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;

/**
 * Ensures that the application is not indexed by search engines.
 *
 * @author Gary PEGEOT <garypegeot@gmail.com>
 */
class DisallowRobotsIndexingListener implements EventSubscriberInterface {
    private const HEADER_NAME = 'X-Robots-Tag';
    public function onResponse(ResponseEvent $event) : void {
        if (!$event->getResponse()->headers
            ->has(static::HEADER_NAME)) {
            $event->getResponse()->headers
                ->set(static::HEADER_NAME, 'noindex');
        }
    }
    public static function getSubscribedEvents() : array {
        return [
            KernelEvents::RESPONSE => [
                'onResponse',
                -255,
            ],
        ];
    }

}