TYPO3.TYPO3CR

If a persisted object contains a property of type SplObjectStorage and that storage does not contain any objects, the storage itself won't be reconstituted on recreating the persisted object.

Example:

/**
 * A blog
 *
 * @scope prototype
 * @entity
 */
class Blog {

    /**
     * The posts contained in this blog
     *
     * @var \SplObjectStorage
     * @lazy
     */
    protected $posts;

    /**
     * Constructs a new Blog
     */
    public function __construct() {
        $this->posts = new \SplObjectStorage();
    }

    /**
     * Adds a post to this blog
     *
     * @param \F3\Blog\Domain\Model\Post $post
     * @return void
     */
    public function addPost(\F3\Blog\Domain\Model\Post $post) {
        $post->setBlog($this);
        $this->posts->attach($post);
    }

    /**
     * Returns all posts in this blog
     *
     * @return \SplObjectStorage
     * @author Robert Lemke <robert@typo3.org>
     */
    public function getPosts() {
        if ($this->posts instanceof \F3\FLOW3\Persistence\LazyLoadingProxy) {
            $this->posts->_loadRealInstance();
        }
        return clone $this->posts;
    }

}
?>

If the Blog contains no Posts, getPosts() will return a clone of the empty SplObjectStorage. However, if the Blog has been reconstituted, $this->posts is NULL and therefore issues a fatal error on cloning $this->posts.