https://blog.sznapka.pl/injecting-repositories-to-service-in-symfony2/ - code snippet 2

code.php

<?php

namespace Example\FooBundle\Repository;

use Doctrine\ORM\EntityRepository;

class FooRepository extends EntityRepository 
                    implements FooRepositoryInterface
{
    public function fetchLatest()
    {
        // create query builder and fetch items sorted by date descending
    }
}