Using UUID as identifier for SonataMediaBundle media entity. File path generates in `/context/year-month/day/filename.ext ` way.

Media.php

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;
use Sonata\MediaBundle\Entity\BaseMedia as BaseMedia;

/**
 * @ORM\Entity(repositoryClass="App\Repository\MediaRepository")
 */
class Media extends BaseMedia
{
    /**
     * @ORM\Id
     * @ORM\Column(name="id", type="guid")
     * @ORM\GeneratedValue(strategy="UUID")
     */
    protected $id;
}

service.yaml

    providers:
        file:
            generator:  'App\Bundles\Sonata\MediaBundle\Generator\UuidGenerator'

        image:
            generator:  'App\Bundles\Sonata\MediaBundle\Generator\UuidGenerator'

UuidGenerator.php

<?php

namespace App\Bundles\Sonata\MediaBundle\Generator;

use Ramsey\Uuid\Uuid;
use Sonata\MediaBundle\Model\MediaInterface;
use Sonata\MediaBundle\Generator\GeneratorInterface;

class UuidGenerator implements GeneratorInterface
{
    /**
     * {@inheritdoc}
     */
    public function generatePath(MediaInterface $media)
    {
        $uuid = Uuid::fromString($media->getId());
        
        /**
         * You can also wrap levels with somthing linke md5() to
         * encode date in path for end-users.
         */
        $rep_first_level = ($uuid->getDateTime()->format('Y-m'));
        $rep_second_level = ($uuid->getDateTime()->format('d'));

        return sprintf('%s/%s/%s', $media->getContext(), $rep_first_level, $rep_second_level);
    }
}