Doctrine 2 association overwrite - php

Question

I have a question about Doctrine 2 and the ability (or not?) to extend an association between to classes.
Best explained with an example :)
Let's say I have this model (code is not complete):
/**
* #Entity
*/
class User {
/**
* #ManyToMany(targetEntity="Group")
* #var Group[]
*/
protected $groups;
}
/**
* #Entity
*/
class Group {
/**
* #ManyToMany(targetEntity="Role")
* #var Role[]
*/
protected $roles;
}
/**
* #Entity
*/
class Role {
/**
* #ManyToOne(targetEntity="RoleType")
* #var RoleType
*/
protected $type;
}
/**
* #Entity
*/
class RoleType {
public function setCustomDatas(array $params) {
// do some stuff. Default to nothing
}
}
Now I use this model in some projects. Suddenly, in a new project, I need to have a RoleType slightly different, with some other fields in DB and other methods. Of course, it was totally unexpected.
What I do in the "view-controller-but-not-model" code is using services:
// basic configuration
$services['RoleType'] = function() {
return new RoleType();
};
// and then in the script that create a role
$role_type = $services['RoleType'];
$role_type->setCustomDatas($some_params);
During application initialization, I simply add this line to overwrite the default RoleType
$services['RoleType'] = function() {
return new GreatRoleType();
};
Ok, great! I can customize the RoleType call and then load some custom classes that do custom things.
But... now I have my model. The model says that a Role targets a RoleType. And this is hard-written. Right now, to have my custom changes working, I need to extend the Role class this way:
/**
* #Entity
*/
class GreatRole extends Role {
/**
* Changing the targetEntity to load my custom type for the role
* #ManyToOne(targetEntity="GreatRoleType")
* #var RoleType
*/
protected $type;
}
But then, I need to extend the Group class to target GreatRole instead of Role.
And in the end, I need to extend User to target GreatGroup (which targets GreatRole, which targets GreatRoleType).
Is there a way to avoid this cascade of extends? Or is there a best practice out there that is totally different from what I did?
Do I need to use MappedSuperClasses? The doc isn't very explicit...
Thanks for your help!
--------------------------- EDIT ---------------------------
If I try to fetch all the hierarchy from User, that's when I encounter problems:
$query
->from('User', 'u')
->leftJoin('u.groups', 'g')
->leftJoin('g.roles', 'r')
->leftJoin('r.type', 't');
If I want to have a "r.type" = GreatRoleType, I need to redefine each classes.