Symfony 3 : How to access my database inside my provider? (with doctrine) - symfony

Question

I would like to access my database that contains all my user inside my provider with doctrine. I followed a tutorial (http://symfony.com/doc/current/security/custom_provider.html) to build my provider for my user, so I have an loadUserByUsername function :
public function loadUserByUsername($username)
{
// make a call to your webservice here
$player = new Player();
$player = $this->getDoctrine()
->getRepository('AppBundle:Player')
->findOneByPseudo($username);
// pretend it returns an array on success, false if there is no user
if ($player) {
return $player;
}
throw new UsernameNotFoundException(
sprintf('Username "%s" does not exist.', $username)
);
}
But of course my getDoctrine() function is undefined. So there is something I don't understand with the provider, I am trying to use it to be authenticated when I login so I need a provider, but why I can't search inside my database? How should I write this function? Thank for your help
EDIT :
When I add doctrine by service.yml (and after writting my constructor inside my provider), I have this error :
FatalThrowableError in PlayerProvider.php line 13:
Type error: Argument 1 passed to AppBundle\Security\PlayerProvider::__construct() must be an instance of Doctrine\Bundle\DoctrineBundle\Registry, instance of Doctrine\ORM\EntityManager given, called in /home/jean/PW6/SkA/SkeletonsOnlineV2/skeleton-online/var/cache/dev/appDevDebugProjectContainer.php on line 327
EDIT 2 : When I just put arguments: ['#doctrine'] inside my service.yml, I get an error that says that doctrine is undefined
EDIT 3 : It works now, I just made a dumb mistake

Answer 1

If you read further, it says the following (emphasis mine):
The real implementation of the user provider will probably have some dependencies or configuration options or other services. Add these as arguments in the service definition.
So in your case it would be something like
# app/config/services.yml
services:
app.webservice_user_provider:
class: AppBundle\Security\User\WebserviceUserProvider
arguments: ['#doctrine']
And your class needs a constructor
class WebserviceUserProvider implements UserProviderInterface
{
protected $doctrine;
public function __construct (\Doctrine\Bundle\DoctrineBundle\Registry $doctrine)
{
$this->doctrine = $doctrine;
}
// ...
}
Then in your method replace $this->getDoctrine() with just $this->doctine