symfony many to one form collection Error insert into ... constraint violation

I get a logical error but I don't know how the right way to correct it. Any help would be appreciate.

So, I've 2 entities User and Address. An address can not be created without a User.

I've a Many to One relationship (Many Addresses to One User).

When I try to register a User, I get this error :

An exception occurred while executing 'INSERT INTO ...

SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'UserID' cannot be null 

Logic because user doesn't exist. But is there a way to say to symfony save my user, get the user id and then persist the address ?

Address Entity

/**
 * @ORM\ManyToOne(targetEntity="CTC\Bundle\UserBundle\Entity\User", inversedBy="addresses")
 * @ORM\JoinColumn(name="UserID", referencedColumnName="id", nullable=false)
 */
private $user;

User Entity (I'm using FOSUser)

/**
 * @ORM\OneToMany(targetEntity="CTC\Bundle\AddressBundle\Entity\Address", mappedBy="user", cascade={"persist"})
 * @ORM\JoinColumn(name="AddressID", referencedColumnName="AddressID", nullable=false)
 */
private $addresses;


public function __construct()
{
    parent::__construct();        
    $this->addresses = new ArrayCollection();
}

The registration type

...

$builder->add('addresses','collection', array(
            'type'=>new AddressType(),
            'allow_add'    => true,
            'allow_delete' => true
        ));

...