Doctrine2 OneToMany relation is null within the same request - orm

Question

So i have the following mapping:
Order entity
/**
* Order
*
* #ORM\Table(name="`order`")
* #ORM\Entity
*/
class Order
{
/**
* #var integer
*
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="IDENTITY")
*/
private $id;
// ... //
/**
* #ORM\OneToMany(targetEntity="OrderItem", mappedBy="order")
*/
private $items;
// ... //
OrderItem entity
/**
* OrderItem
*
* #ORM\Table(name="order_item")
* #ORM\Entity
*/
class OrderItem
{
/**
* #var integer
*
* #ORM\Column(type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="IDENTITY")
*/
private $id;
// ... //
/**
* #ORM\ManyToOne(targetEntity="Order", inversedBy="items")
* #ORM\JoinColumn(referencedColumnName="id")
*/
private $order;
// ... //
The problem I experience is when I try to dump $order->getItems() after flushing it remains NULL. Eveything is inserted fine to the database with the correct ids and when I try to get the order in the NEXT request it does contain items in $order->getItems() so no doubt it does work.
But it does not work (giving NULL) with the same request.
Look at the code below:
$manager = $this->getDoctrine()->getManager();
$order = new Order();
$orderItem = new OrderItem();
$orderItem
->setOrder($order)
;
$manager->persist($order);
$manager->persist($orderItem);
dump($order->getItems()); // returns NULL
// but in the next request it will contain items
So how can I get those items within the same request? I need to generate the order and return the items... any idea?

Answer 1

In class OrderItem, maybe.
public setOrder(Order $order)
{
$order->addItem($this);
$this->ordder = $order;
}