Symfony 4 get authentification with cas and roles via database - symfony

Question

I am having trouble finding any help, examples or tutorials that layout how to use CAS for Authorization but load the roles from a local database in Symfony 4.
I managed to authenticate via CAS using the bundle: prayno. I manage to succesfully get roles from a database via an entity and repository. But the fact is that I did not manage to make the link between the twos.
Here is my security.yaml:
security:
# https://symfony.com/doc/current/security.html#where-do-users-come-from- user-providers
providers:
cas:
id: prayno.cas_user_provider
firewalls:
dev:
pattern: ^/(_(profiler|wdt)|css|images|js)/
security: false
main:
anonymous: ~
logout: ~
guard:
authenticators:
- prayno.cas_authenticator
The function under the prayno bundle to get authentification and the roles:
public function loadUserByUsername($username)
{
if ($username) {
$password = '...';
$salt = "";
$roles = ['ROLE_USER'];
return new CasUser($username, $password, $salt, $roles);
}
throw new UsernameNotFoundException(
sprintf('Username "%s" does not exist.', $username)
);
}
From there, I tried to get my roles from the database using the controller I created for this occasion:
<?php
namespace App\Controller;
use App\Entity\FscDroitsBundle;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\Routing\Annotation\Route;
class RightsController extends AbstractController
{
/**
* #Route("/rights", name="rights")
*/
public function attribute_rights($netid)
{
$entities = $this->em->getDoctrine()->getRepository(FscDroitsBundle::class)->findRights($netid);
$rights_array = array('ROLE_USER');
foreach ($entities as $data) {
array_push($rights_array, $data->getBundle());
}
return $rights_array;
}
But, until now, I did not find any way to use this controller in the bundle, something like:
$rights = new RightsController();
$roles = $rights->attribute_rights($username);
instead of:
$roles = ['ROLE_USER'];
in my loadbyUsername function.
The problem seems to come from this line:
$entities = $this->getDoctrine()->getRepository(FscDroitsBundle::class)->findRights($netid);
The error is: Call to a member function has() on null
How is it that the controller can not access the repository in the bundle meanwhile it access it without any problem on a view ?