/**
  * @param LifecycleEventArgs $args
  * @param string             $event
  */
 protected function handleEvent(LifecycleEventArgs $args, $event)
 {
     $object = $args->getObject();
     $om = $args->getObjectManager();
     $class = get_class($object);
     $classMetadata = $this->metadataFactory->getMetadataForClass($class);
     $classMetadataInfo = $om->getClassMetadata($class);
     $identifierFields = $classMetadataInfo->getIdentifierFieldNames();
     foreach ($classMetadata->propertyMetadata as $propertyMetadata) {
         if ($propertyMetadata instanceof PropertyMetadata && count($propertyMetadata->slugFields)) {
             $hasIdentifierFields = count(array_intersect($identifierFields, $propertyMetadata->slugFields)) > 0;
             if ($event == 'prePersist' && $hasIdentifierFields || $event == 'postPersist' && !$hasIdentifierFields) {
                 continue;
                 // generate slug in another event
             }
             $slug = null;
             if ($event == 'preUpdate') {
                 if ($args->hasChangedField($propertyMetadata->name)) {
                     // generate custom slug
                     $slug = $this->slugger->slugify($args->getNewValue($propertyMetadata->name), $propertyMetadata->slugSeparator);
                 } elseif (null !== $propertyMetadata->getValue($object)) {
                     continue;
                     // no changes
                 }
             } else {
                 // generate custom slug
                 $slug = $this->slugger->slugify($propertyMetadata->getValue($object), $propertyMetadata->slugSeparator);
             }
             if (!trim($slug)) {
                 // generate slug from the sluggable fields
                 $slug = $this->generateSlugFromMetadata($object, $propertyMetadata->slugFields, $propertyMetadata->slugSeparator);
             }
             $id = $event == 'preUpdate' && method_exists($object, 'getId') ? $object->getId() : null;
             // generate unique slug
             $slug = $this->generateUniqueSlug($om, $object, $propertyMetadata->name, $slug, $propertyMetadata->slugSeparator, $id);
             $propertyMetadata->setValue($object, $slug);
             $this->recomputeSingleObjectChangeSet($om, $object);
         }
     }
 }