Cannot fetch the Doctrine EntityManager with autowire in Symfony

Well, I'm going crazy, there's something I don't get with the Symfony (3.3) autowiring stuff. I've read those resources : http://symfony.com/doc/current/service_container.html http://symfony.com/doc/current/service_container/3.3-di-changes.html and others that I can't post because I need 10 reputation. I've also read many articles/stackoverflow posts, but with no luck.

I've tried to set up my services, and it almost works, it's just that the EntityManager is null, so I can't call ->getRepository() on it. The error happens on the line like this in my factory:

$databaseTournament = $this->em->getRepository('AppBundle:Tournament')
    ->find($tournament);

"Call to a member function getRepository() on null"

It seems to find the services correctly but never injects the EntityManager in the factory. I've tried to configure things explicitely in the services.yml, but I never managed to make it work.

I'm trying to figure it ou since yesterday, but I'm getting really confused. Could you help me ? Thank you in advance ! :)

Here are my files :

services.yml:

parameters:
services:
    _defaults:
        autowire: true
        autoconfigure: true
        public: false
    AppBundle\:
        resource: '../../src/AppBundle/*'
        exclude: '../../src/AppBundle/{Entity,Repository,Tests}'
    AppBundle\Controller\:
        resource: '../../src/AppBundle/Controller'
        public: true
        tags: ['controller.service_arguments']

EntryFactory:

<?php
namespace AppBundle\Factory;

use AppBundle\Entity\Entry;
use AppBundle\Entity\Team;
use AppBundle\Entity\Tournament;
use AppBundle\Exception\InvalidEntryArgumentException;
use Doctrine\ORM\EntityManagerInterface;
use Doctrine\ORM\EntityNotFoundException;

class EntryFactory
{
    private $em;

    public function __construct(EntityManagerInterface $em)
    {
        $this->em = $em;
    }

    public function createEntry($tournament, $team, $eliminated = false)
    {
        $entry = new Entry();

        if ($tournament instanceof Tournament) {
            $entry->setTournament($tournament);
        }
        elseif (is_int($tournament) && $tournament >= 0) {
            $databaseTournament = $this->em->getRepository('AppBundle:Tournament')->find($tournament);
            if (is_null($databaseTournament)) {
                throw new EntityNotFoundException('Tournament (id:'.$tournament.') not found.');
            }
            else {
                $entry->setTournament($databaseTournament);
            }
        }
        else {
            throw new InvalidEntryArgumentException('Could not determine the Tournament argument.');
        }

        if ($team instanceof Team) {
            $entry->setTeam($team);
        }
        elseif (is_int($team) && $team >= 0) {
            $databaseTeam = $this->em->getRepository('AppBundle:Team')->find($team);
            if (is_null($databaseTeam)) {
                throw new EntityNotFoundException('Team (id:'.$team.') not found.');
            }
            else {
                $entry->setTeam($databaseTeam);
            }
        }
        else {
             throw new InvalidEntryArgumentException('Could not determine the Team argument.');
        }


        $entry->setEliminated($eliminated);
        return $entry;
    }
}

EntryController:

<?php

namespace AppBundle\Controller;

use AppBundle\Entity\Entry;
use Doctrine\ORM\EntityNotFoundException;
use FOS\RestBundle\Controller\Annotations as Rest;
use FOS\RestBundle\Controller\FOSRestController;
use FOS\RestBundle\View\View;
use Nelmio\ApiDocBundle\Annotation\ApiDoc;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\ParamConverter;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Validator\ConstraintViolationList;
use AppBundle\Factory;

class EntryController extends FOSRestController
{
    /**
     * @ApiDoc(
     *     resource=true,
     *     section="Entries",
     *     description="Creates a new entry.",
     *     statusCodes={
     *          201="Returned when created.",
     *          400="Returned when a violation is raised by validation.",
     *          404="Returned when a team or a tournament is not found."
     *     }
     * )
     *
     * @Rest\Post(
     *     path="/entries",
     *     name="app_entry_create"
     * )
     * @Rest\View(statusCode=201)
     * @Rest\RequestParam(
     *     name="tournamentId",
     *     requirements="\d+",
     *     nullable=false,
     *     description="The id of the tournament in which the team enters."
     * )
     * @Rest\RequestParam(
     *     name="teamId",
     *     requirements="\d+",
     *     nullable=false,
     *     description="The id of the team entering the tournament."
     * )
     *
     * @param $tournamentId
     * @param $teamId
     * @param ConstraintViolationList $violationList
     * @param Factory\EntryFactory $entryFactory
     * @return Entry|View
     * @throws EntityNotFoundException
     * @internal param $id
     * @internal param Entry $entry
     */
    public function createEntryAction($tournamentId, $teamId, ConstraintViolationList $violationList,
                                      Factory\EntryFactory $entryFactory)
    {
        if (count($violationList)) {
            return $this->view($violationList, Response::HTTP_BAD_REQUEST);
        }
        $entry = $entryFactory->createEntry($tournamentId,$teamId);
        $em->persist($entry);
        $em->flush();
        return $entry;
    }
}

edit:

I must add that I've tried this and it doesn't work either:

in the services.yml:

AppBundle\Factory\EntryFactory:
    public: true
    arguments: ['@doctrine.orm.entity_manager']

in the EntryFactory:

public function __construct(EntityManager $em)
{
    $this->em = $em;
}

edit 2:

I've also tried to disable everything new : still the same error

AppBundle\Factory\EntryFactory:
        autowire: false
        autoconfigure: false
        public: true
        arguments:
            $em: '@doctrine.orm.entity_manager'

Same with disabling the folder in the default config :

AppBundle\:
        resource: '../../src/AppBundle/*'
        exclude: '../../src/AppBundle/{Entity,Repository,Tests,Factory}'