在show动作中显示媒体

Question

I use Sonata to make an app and I am facing some problem with MediaBundle. I Have two entities :

Product & ProductImage

Inside Product I have this :

/**
 * @ORM\ManyToMany(targetEntity="ProductImage", cascade={"persist"}, fetch="LAZY", indexBy="ASC")
 */
protected $medias;

Inside ProductImage :

/**
 * @ORM\ManyToOne(targetEntity="Product", cascade={"persist"}, fetch="LAZY")
 */
protected $Product;

/**
 * @ORM\ManyToOne(targetEntity="AppBundle\Entity\Media\Media", cascade={"persist"}, fetch="LAZY")
 */
protected $image;

public function __toString()
{
    global $kernel;

    $provider = $kernel->getContainer()->get($this->getImage()->getProviderName());
    return $provider->generatePublicUrl($this->getImage(),'small');
}

In my ProductAdmin.php file :

public function configureShowFields(ShowMapper $showMapper)
{
    $showMapper
        ->add('name')
        ->end()
        ->with('Medias', array('class' => 'col-md-12'))
        ->add('medias', 'sonata_type_collection', array(), array(
            'inline' => 'table',
            'sortable'  => 'position'
        )) 
        ->end();
}

When I go to the show page ( .../product/6/show), I have all my information correctly display but medias is just a list of public URL. How can I display each image instead of URL ?

Thanks