Using php doctrine with CrateDB

Hi All, We are using the php doctrine with crate. But now we want to insert a new doc and use the _id field. But this we cant get to work. How do we set this up so the _id is added by crate automatically? This is not working:

     * @ORM\Id()
     * @ORM\Column(type="string", name="_id")
     * @ORM\GeneratedValue(strategy="AUTO")
    private $id;

The _id column is not writeable, it will be always generated by CrateDB. Removing the GeneratedValue annotation should solve it.