namespace Application\Model;

interface ProductManagerInterface
{
    public function findOneBy($field, $value);
    public function findDeletedProducts();
}

namespace Application\Entity;

use Application\Model\ProductManagerInterface;

class ProductManager implements ProductManagerInterface
{
    protected $em;
    protected $class;
    protected $repository;

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

    public function findOneBy($field, $value)
    {
        return $this->getRepository()->findOneBy($field, $value);
    }

    public function findDeletedProducts()
    {
        return $this->getRepository()->findDeletedProducts();
    }

    public function getRepository()
    {
        return $this->em->getRepository($this->class);
    }
}

namespace Application\Entity\Repository;

use Doctrine\ORM\EntityRepository;

class ProductRepository extends EntityRepository
{
    public function findDeletedProducts()
    {
        return $this->_em->createQuery('SELECT p FROM Application\Entity\Product p WHERE p.deleted = true');
    }
}

namespace Application\Controller;

class ProductController extends Controller
{
    public function showAction()
    {
        //DiC container, encargado de ensamblar el manager inyectando las dependencias
        $product = $this->get('product_manager')->findOneBy('slug', 'my-custom-product');
        return array('product' => $product);
    }
}