Symfony form + DropZonejs

MediaController.php

<?php

namespace App\Controller\Admin;

use App\Entity\Media;
use App\Form\MediaType;
use App\Repository\MediaRepository;
use App\Service\FileUploader;
use phpDocumentor\Reflection\Types\This;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\File\UploadedFile;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\Session\SessionInterface;
use Symfony\Component\Routing\Annotation\Route;

/**
 * @Route("admin/media")
 */
class MediaController extends AbstractController
{
    private $session;

    public function __construct(SessionInterface $session)
    {
        $this->session = $session;
        //$this->session->remove('image-file-name');

        dump($session->all());
    }

    /**
     * @Route("/", name="admin_media_index", methods={"GET"})
     * @param MediaRepository $mediaRepository
     * @return Response
     */
    public function index(MediaRepository $mediaRepository): Response
    {
        return $this->render('admin/media/index.html.twig', [
            'media' => $mediaRepository->findAll(),
        ]);
    }

    /**
     * @Route("/new/upload", name="admin_media_upload_image", methods={"POST"})
     * @param Request $request
     * @param FileUploader $fileUploader
     * @return Response
     */
    public function uploadImage(Request $request, FileUploader $fileUploader): Response
    {
        /** @var UploadedFile $uploadedFile **/
        $uploadedFile = $request->files->get('media')['fileName'];

        $imageFileName = '';
        if ($uploadedFile) {
            $imageFileName = $fileUploader->upload($uploadedFile);
            $this->session->set('file_name', $imageFileName);
        }

        $response = new Response();
        $response->setContent(json_encode([
            'message' => 'success',
            'fileName' => $imageFileName,
            'session_id' => $this->session->getId(),
            'Session' => $this->session->all(),
        ]));
        $response->headers->set('Content-Type', 'application/json');

        return $response;
    }

    /**
     * @Route("/new", name="admin_media_new", methods={"GET","POST"})
     * @param Request $request
     * @return Response
     */
    public function new(Request $request): Response
    {
        if ($request->getMethod() === 'GET') {
            $this->session->remove('file_name');
        }

        $medium = new Media();
        $form = $this->createForm(MediaType::class, $medium);

        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
            $entityManager = $this->getDoctrine()->getManager();
            $entityManager->persist($medium);
            $entityManager->flush();

            //$this->session->remove('file_name');

            return $this->redirectToRoute('admin_media_index');
        }

        return $this->render('admin/media/new.html.twig', [
            'medium' => $medium,
            'form' => $form->createView(),
        ]);
    }

    /**
     * @Route("/{id}/edit", name="admin_media_edit", methods={"GET","POST"})
     * @param Request $request
     * @param Media $medium
     * @return Response
     */
    public function edit(Request $request, Media $medium): Response
    {
        $form = $this->createForm(MediaType::class, $medium);
        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
            $this->getDoctrine()->getManager()->flush();

            return $this->redirectToRoute('admin_media_index');
        }

        return $this->render('admin/media/edit.html.twig', [
            'medium' => $medium,
            'form' => $form->createView(),
        ]);
    }

    /**
     * @Route("/{id}", name="admin_media_delete", methods={"DELETE"})
     * @param Request $request
     * @param Media $medium
     * @return Response
     */
    public function delete(Request $request, Media $medium): Response
    {
        if ($this->isCsrfTokenValid('delete'.$medium->getId(), $request->request->get('_token'))) {
            $entityManager = $this->getDoctrine()->getManager();
            $entityManager->remove($medium);
            $entityManager->flush();
        }

        return $this->redirectToRoute('admin_media_index');
    }
}

MediaType.php

<?php

namespace App\Form;

use App\Entity\Media;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\Extension\Core\Type\FileType;
use Symfony\Component\Form\Extension\Core\Type\SubmitType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\FormEvents;
use Symfony\Component\HttpFoundation\Session\SessionInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Validator\Constraints\Image;
use Symfony\Component\Form\FormEvent;

class MediaType extends AbstractType
{
    private $session;

    public function __construct(SessionInterface $session)
    {
        $this->session = $session;
        //$this->session->remove('file_name');
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('fileName')
            ->add('alt')
            ->add('title')
            ->add('submit', SubmitType::class);

        $builder->addEventListener(
            FormEvents::POST_SET_DATA,
            function (FormEvent $event) {

                $form = $event->getForm();
                $data = $event->getData();
                /*if ($this->session->has('file_name')) {
                    //$data['fileName'] = $this->session->get('file_name');
                    $data->setFileName($this->session->get('file_name'));
                }*/
                $form->get('fileName')->setData($this->session->get('file_name'));
                //$data->setFileName($this->session->get('file_name'));
                dump($event);
                dump($this->session->get('file_name'));
                dump($form->get('fileName')->getData());
            }
        );
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            'data_class' => Media::class,
        ]);
    }
}