Symfony2: PrePersist/PreUpdate lifecycle-event not fired - events

Question

Two Entities GalleryAlbum and GalleryImage have OneToMany/ManyToOne relationship:
One GalleryAlbum ==== can have ====> Many GalleryImage
Many GalleryImage === can be in ===> One GalleryAlbum
(sources below)
What is the problem?
Adding (uploading) files to GalleryAlbum
$em->persist($album)
$em->flush()
For each uploaded file GalleryAlbum class creates and adds to $images a new GalleryImage entity
My ECHO/EXIT test is not shown (GalleryImage's prePersist/preUpdate event callback function named preUpload is not triggered!)
My new images are not saved to the database? Why?
What is weird! If I do:
Adding (uploading) files
$em->persist($album)
$em->flush()
again $em->flush()
My ECHO/EXIT test is shown (GalleryImage's prePersist/preUpdate event callback function named preUpload is triggered!)
(if i delete echo/exit) My new GalleryImages are saved now!!!
Why?
Why is preUpload never triggered when I flush() once, and is triggered when I flush() twice?
# src GalleryAlbum.php
/**
* #ORM\Entity
* #ORM\HasLifecycleCallbacks
* #ORM\Table(name="gallery_album")
*/
class GalleryAlbum
{
// some properties like id, name, description, etc
/**
* #ORM\OneToMany(targetEntity="GalleryImage", mappedBy="parent")
*/
protected $images;
/* Files container. Used for upload service. Must not be persisted. */
protected $files;
/* #ORM\Column(type="boolean", nullable=TRUE)
*
* if set to true will updateing object and calling preUpdate event callback
* becouse it's always set to null in database by prePersist event callback */
protected $files_added;
/**
* Set container files
*
* #return GalleryAlbum
*/
public function setFiles($files)
{
$this->files = $files;
$this->files_added = true;
/* setting files_added to true forces EntityManager to update
* this GalleryAlbum even if no other properties have changed */
return $this;
}
/**
* #ORM\PrePersist()
* #ORM\PreUpdate()
*/
public function preUpload()
{
if(null !== $this->files) {
foreach($this->files as $key => $file) {
$this->addGalleryElement($file);
unset($this->files[$key]);
}
}
/* Resetting property files_added to NULL
* so it always stays null in database */
$this->files_added = null;
}
/**
* Constructing new GalleryImage and setting it's file and parent
*/
public function addGalleryElement($file)
{
$element = new GalleryImage($this, $file);
$this->addGalleryImage($element);
}
}
# src GalleryImage.php
/**
* #ORM\Entity
* #ORM\HasLifecycleCallbacks
* #ORM\Table(name="gallery_image")
*/
class GalleryImage
{
// some properties like id, name, description, etc
/**
* #ORM\ManyToOne(targetEntity="GalleryAlbum", inversedBy="images")
* #ORM\JoinColumn(name="parent_id", referencedColumnName="id")
*/
protected $parent;
/* Constructing new GalleryImage */
public function __construct($parent = null, $file = null)
{
if($parent) $this->setParent($parent);
if($file) $this->setFile($file);
}
/**
* #ORM\PrePersist()
* #ORM\PreUpdate()
*/
public function preUpload()
{
echo 'TEST: is this event callback function fired?'; exit;
if(null !== $this->file) {
$this->path = $this->file->guessExtension();
}
$this->file_added = null;
}
}

Answer 1

The first time you call persist doctrine will only save $album and not its images. You must specify that you want doctrine to cascade the persist by specifying it in the $images declaration:
/**
* #ORM\OneToMany(targetEntity="GalleryImage", mappedBy="parent", cascade={"persist", "remove"})
*/
protected $images;
This way when you call persist($album) it will also persist your images and should trigger preUpload in your GalleryImage. There are a few different options available for cascading and they are explained well here:
Doctrine transitive persistence cascade operations