code: public function handle(PostPersistModelEvent $event)
      {
          if (!$this->wantToHandle($event)) {
              return;
          }
  
          $old         = $event->getOriginalModel();
          $new         = $event->getModel();
          $oldInstance = $old->getProperty('pid') ? $this->createAttributeInstance($old) : null;
          $newInstance = $this->createAttributeInstance($new);
  
          // If type or column name has been changed, destroy old data and initialize new.
          if ($this->isAttributeNameOrTypeChanged($new, $old)) {
              // Destroy old instance.
              if ($oldInstance) {
                  $oldInstance->destroyAUX();
              }
  
              // Create new instance aux info.
              if ($newInstance) {
                  $newInstance->initializeAUX();
              }
          }
  
          if ($newInstance) {
              // Now loop over all values and update the meta in the instance.
              foreach ($new->getPropertiesAsArray() as $strKey => $varValue) {
                  $newInstance->handleMetaChange($strKey, $varValue);
              }
          }
      }
docs: Handle the update of an attribute and all attached data.
  
  @param PostPersistModelEvent $event The event.
  
  @return void