Many-to-Many Relations using non-"id" Primary Key in Doctrine - doctrine

Question

So I'd like to create two entities and make a many-to-many reference. I would love to make this association using a string primary key on one table. This seems to be really hard, at least it took me pretty much time trying without any results yet.
This is my approach:
First entity:
namespace Project\AdminBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity
* #ORM\Table(name="User")
*/
class User
{
/**
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $Id;
/**
* #ORM\ManyToMany(targetEntity="Role", inversedBy="Users")
* #ORM\JoinTable(name="role_user",
* joinColumns={#ORM\JoinColumn(name="User_Id", referencedColumnName="Id")},
* inverseJoinColumns={#ORM\JoinColumn(name="Role_Name", referencedColumnName="Name")}
* )
*/
private $Roles;
}
And the second:
namespace Project\AdminBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Entity
* #ORM\Table(name="Role")
*/
class Role
{
/**
* #ORM\Id
* #ORM\Column(type="string", length=256)
*/
private $Name;
/**
* #ORM\ManyToMany(targetEntity="User", mappedBy="Roles")
* #ORM\JoinTable(name="role_user",
* joinColumns={#ORM\JoinColumn(name="Role_Name", referencedColumnName="Name")},
* inverseJoinColumns={#ORM\JoinColumn(name="User_Id", referencedColumnName="Id")}
* )
*/
private $Users;
}
Output of ./app/console doctrine:schema:validate:
[Mapping] FAIL - The entity-class 'Project\AdminBundle\Entity\User' mapping is invalid:
* The referenced column name 'Id' has to be a primary key column on the target entity class 'Project\AdminBundle\Entity\User'.
* The referenced column name 'Id' has to be a primary key column on the target entity class 'Project\AdminBundle\Entity\Role'.
What do I miss?

Answer 1

Attention upper/lowercase! Doctrine generates its columns as lowercase per default. This solves the issue:
* joinColumns={#ORM\JoinColumn(name="User_Id", referencedColumnName="id")},
* inverseJoinColumns={#ORM\JoinColumn(name="Role_Name", referencedColumnName="name")}
This it over-complicated; it's enough to put this into the Role entity:
/**
* #ORM\ManyToMany(targetEntity="User", mappedBy="Roles")
* #ORM\JoinColumn(name="role_user", referencedColumnName="name")
*/
private $Users;
I only thought about this when writing the question.. what a good method to think about the problem again from scratch.
Cheers