Форма Symfony: Загруженный файл — «Это значение должно быть строкового типа»

[ОБНОВЛЕНО]: 2019/06/24 - 23;28

Загружая файл с формой, я сталкиваюсь со следующей ошибкой:

This value should be of type string

Конструктор форм настроен на FileType, как и должно быть:

FormType

class DocumentType extends AbstractType {
    public function buildForm(FormBuilderInterface $builder, array $options) {
        /** @var Document $salle */
        $document=$options['data']; //Unused for now
        $dataRoute=$options['data_route']; //Unused for now

        $builder->add('nom')
                ->add('description')
                ->add('fichier', FileType::class, array(
                    //'data_class' is not the problem, tested without it.
                    //see comments if you don't know what it does.
                    'data_class'=>null,
                    'required'=>true,
                ))
                ->add('isActif', null, array('required'=>false));
    }

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

И у моего геттера и сеттера нет подсказки типа, чтобы убедиться, что UploadedFile::__toString() не будет вызываться:

Entity

class Document {
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type = "integer")
     */
    private $id;
    /**
     * @ORM\Column(type = "string", length=100)
     */
    private $nom;
    /**
     * @ORM\Column(type = "string", length=40)
     */
    private $fichier;
    /**
     * @ORM\Column(type = "boolean")
     */
    private $isActif;
    /**
     * @ORM\ManyToOne(targetEntity = "App\Entity\Salle", inversedBy = "documents")
     * @ORM\JoinColumn(onDelete = "CASCADE")
     */
    private $salle;
    /**
     * @ORM\ManyToOne(targetEntity = "App\Entity\Stand", inversedBy = "documents")
     * @ORM\JoinColumn(onDelete = "CASCADE")
     */
    private $stand;

    public function __construct() {
        $this->isActif=true;
    }

    public function __toString() {
        return $this->getNom();
    }

    public function getId(): ?int {
        return $this->id;
    }

    public function getNom(): ?string {
        return $this->nom;
    }

    public function setNom(string $nom): self {
        $this->nom=$nom;

        return $this;
    }

    public function getFichier()/*Removed type hint*/ {
        return $this->fichier;
    }

    public function setFichier(/*Removed type hint*/$fichier): self {
        $this->fichier=$fichier;

        return $this;
    }

    public function getIsActif (): ?bool {
        return $this->isActif;
    }

    public function setIsActif (bool $isActif): self {
        $this->isActif=$isActif;

        return $this;
    }

    public function getSalle(): ?Salle {
        return $this->salle;
    }

    public function setSalle(?Salle $salle): self {
        $this->salle=$salle;

        return $this;
    }

    public function getStand(): ?Stand {
        return $this->stand;
    }

    public function setStand(?Stand $stand): self {
        $this->stand=$stand;

        return $this;
    }
}

Тем не менее, валидатор формы по-прежнему ожидает объект string, а не объект UploadedFile.

Controller

/**
 * @Route("/dashboard/documents/new", name = "document_new", methods = {"POST"})
 * @Route("/dashboard/hall-{id}/documents/new", name = "hall_document_new", methods = {"POST"})
 * @Route("/dashboard/stand-{id}/documents/new", name = "stand_document_new", methods = {"POST"})
 * @param Router $router
 * @param Request $request
 * @param FileUploader $fileUploader
 * @param SalleRepository $salleRepository
 * @param Salle|null $salle
 * @param Stand|null $stand
 * @return JsonResponse
 * @throws Exception
 */
public function new(Router $router, Request $request, FileUploader $fileUploader, SalleRepository $salleRepository, Salle $salle=null, Stand $stand=null) {
    if ($this->isGranted('ROLE_ORGANISATEUR')) {
        $route=$router->match($request->getPathInfo())['_route'];
        if (($route == 'hall_document_new' && !$salle) || ($route == 'stand_document_new' && !$stand)) {
            //ToDo [SP] set message
            return $this->json(array(
                'messageInfo'=>array(
                    array(
                        'message'=>'',
                        'type'=>'error',
                        'length'=>'',
                    )
                )
            ));
        }

        $document=new Document();
        if ($route == 'hall_document_new') {
            $action=$this->generateUrl($route, array('id'=>$salle->getId()));
        } elseif ($route == 'stand_document_new') {
            $action=$this->generateUrl($route, array('id'=>$stand->getId()));
        } else {
            $action=$this->generateUrl($route);
        }
        $form=$this->createForm(DocumentType::class, $document, array(
            'action'=>$action,
            'method'=>'POST',
            'data_route'=>$route,
        ));

        $form->handleRequest($request);
        if ($form->isSubmitted()) {
            //Fail here, excepting a string value (shouldn't), got UploadedFile object
            if ($form->isValid()) {
                if ($route == 'hall_document_new') {
                    $document->setSalle($salle);
                } elseif ($route == 'stand_document_new') {
                    $document->setStand($stand);
                } else {
                    $accueil=$salleRepository->findOneBy(array('isAccueil'=>true));
                    if ($accueil) {
                        $document->setSalle($accueil);
                    } else {
                        //ToDo [SP] set message
                        return $this->json(array(
                            'messageInfo'=>array(
                                array(
                                    'message'=>'',
                                    'type'=>'',
                                    'length'=>'',
                                )
                            )
                        ));
                    }
                }

                /** @noinspection PhpParamsInspection */
                $filename=$fileUploader->uploadDocument($document->getFichier());
                if ($filename) {
                    $document->setFichier($filename);
                } else {
                    //ToDo [SP] set message
                    return $this->json(array(
                        'messageInfo'=>array(
                            array(
                                'message'=>'',
                                'type'=>'error',
                                'length'=>'',
                            )
                        )
                    ));
                }

                $entityManager=$this->getDoctrine()->getManager();
                $entityManager->persist($document);
                $entityManager->flush();

                return $this->json(array(
                    'modal'=>array(
                        'action'=>'unload',
                        'modal'=>'mdcDialog',
                        'content'=>null,
                    )
                ));
            } else {
                //ToDo [SP] Hide error message
                return $this->json($form->getErrors(true, true));
                // return $this->json(false);
            }
        }

        return $this->json(array(
            'modal'=>array(
                'action'=>'load',
                'modal'=>'mdcDialog',
                'content'=>$this->renderView('salon/dashboard/document/new.html.twig', array(
                    'salle'=>$salle,
                    'stand'=>$stand,
                    'document'=>$document,
                    'form'=>$form->createView(),
                )),
            )
        ));
    } else {
        return $this->json(false);
    }
}

services.yaml

parameters:
    locale: 'en'
    app_locales: en|fr
    ul_document_path: '%kernel.root_dir%/../public/upload/document/'

services:
    _defaults:
        autowire: true
        autoconfigure: true
        bind:
            $locales: '%app_locales%'
            $defaultLocale: '%locale%'
            $router: '@router'

    App\:
        resource: '../src/*'
        exclude: '../src/{DependencyInjection,Entity,Migrations,Tests,Kernel.php}'

    App\Controller\:
        resource: '../src/Controller'
        tags: ['controller.service_arguments']

    App\Listener\kernelListener:
        tags:
            - { name: kernel.event_listener, event: kernel.request, method: onKernelRequest }
            - { name: kernel.event_listener, event: kernel.response, method: onKernelResponse }
            - { name: kernel.event_listener, event: kernel.exception, method: onKernelException }

    App\Service\FileUploader:
        arguments:
            $ulDocumentPath: '%ul_document_path%'