How persist one to one entity unidirectionally in Symfony2 - symfony

Question

I have a problem with two entities in Symfony2 with Doctrine:
This is the first Entity:
/**
* Pedidos
*
* #ORM\Table()
* #ORM\Entity(repositoryClass="RestCarta\Bundle\FrontendBundle\Entity\PedidosRepository")
*/
class Pedidos
{
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var string
*
* #ORM\Column(name="usuario", type="string", length=100)
*/
private $usuario;
/**
* #var string
*
* #ORM\Column(name="mesa", type="string", length=3)
*/
private $mesa;
/**
* #var integer
*
* #ORM\OneToOne(targetEntity="Articulos")
* #ORM\JoinColumn(name="articulo_id", referencedColumnName="id")
*/
private $articulo;
/**
* #var string
*
* #ORM\Column(name="precio", type="decimal")
*/
private $precio;
This is the second Entity:
/**
* Articulos
*
* #ORM\Table()
* #ORM\Entity(repositoryClass="RestCarta\Bundle\FrontendBundle\Entity\ArticulosRepository")
*/
class Articulos
{
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var string
*
* #ORM\Column(name="referencia", type="string", length=100)
*/
private $referencia;
/**
* #var string
*
* #ORM\Column(name="nombre", type="string", length=255)
*/
private $nombre;
/**
* #var string
*
* #ORM\Column(name="descripcion", type="string", length=255)
*/
private $descripcion;
/**
* #var string
*
* #ORM\Column(name="precio", type="decimal")
*/
private $precio;
/**
* #var string
*
* #ORM\Column(name="imagen", type="string", length=255)
*/
private $imagen;
/**
* #ORM\ManyToOne(targetEntity="Categorias", inversedBy="articulos")
* #ORM\JoinColumn(name="categoria_id", referencedColumnName="id")
*/
protected $categoria;
And now the problem.
How i can persist one "Pedido" with contain one "Articulo" ??
I can read all "Pedido" and the LEFT JOIN with "Articulo" work perfectly, (data inserted manually via phpMyAdmin) but when I persist more data with this code:
$em = $this->getDoctrine()->getManager();
$pedido = new Pedidos();
$pedido->setUsuario('blablabla');
$pedido->setMesa('blablabla');
$pedido->setArticulo($identi);
$pedido->setPrecio('blablabla');
$em->persist($pedido);
$em->flush();
$identi = corresponds to an id of "Articulos"
The result is:
Warning: spl_object_hash() expects parameter 1 to be object, string
given in
/Applications/MAMP/htdocs/RestCarta/vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php
line 1388 500 Internal Server Error - ContextErrorException
Please, anyone can help me?
Thanks in Advance

Answer 1

$identi must be a entity object, not only the ID you can use
$em->getReference('YourNamespace\Articulos', $identi);