Modifying A Bolt Record on the Post Save Event

CustomisationExtension.php

<?php
namespace Bundle\Site;

use Bolt\Storage\Entity\Content;
use Bolt\Extension\SimpleExtension;
use Bolt\Events\StorageEvent;
use Bolt\Events\StorageEvents;

/**
 * Site bundle extension loader.
 *
 * This is the base bundle you can use to further customise Bolt for your
 * specific site.
 *
 * It is perfectly safe to remove this bundle, just remember to remove the
 * entry from your .bolt.yml or .bolt.php file.
 *
 * For more information on building bundles see https://docs.bolt.cm/extensions
 */
class CustomisationExtension extends SimpleExtension
{
  
    public static function getSubscribedEvents()
    {
        return [
            StorageEvents::PRE_SAVE => [
                ['onPreSave', 0],
            ],
        ];
    }
  
    /**
     * StorageEvents::PRE_SAVE event callback.
     *
     * @param StorageEvent $event
     */
    public function onPreSave(StorageEvent $event)
    {
        $contentRecord = $event->getSubject();
        $contentTypeName = (string) $contentRecord->getContentType();
        if (!$contentRecord instanceof Content || !$contentTypeName === 'events') {
            return;
        }
      
      
        $eventDate = strtotime($contentRecord->getEventdate());
        $depublishTime = strtotime('+2 days', $eventDate);
      
        $contentRecord->setDatedepublish($depublishTime);
        
    }
}