The form's view data is expected to be an instance of class … but is a(n) string

问题

I am currently receiving the following error:

"The form's view data is expected to be an instance of class Symfony\Component\HttpFoundation\File\File, but is a(n) string. You can avoid this error by setting the "data_class" option to null or by adding a view transformer that transforms a(n) string to an instance of Symfony\Component\HttpFoundation\File\File."

SoundController - upload function

 /**
 * @Security("is_granted('IS_AUTHENTICATED_FULLY')")
 * @Route("/song/upload", name="upload_song")
 * @param Request $request
 * @return \Symfony\Component\HttpFoundation\Response
 */
public function uploadSong(Request $request)
{
    $song = new Sound();

    $form = $this->createForm(SoundType::class, $song);
    $form->handleRequest($request);

    if ($form->isSubmitted() && $form->isValid())
    {
        $file = $song->getFile();
        $user = $this->getUser();

        $fileName = $this
            ->get('app.file_uploader')
            ->setDir($this->get('kernel')->getRootDir()."/../web".$this->getParameter('songs_directory'))
            ->upload($file);

        $song->setFile($fileName);

        $file = $song->getCoverFile();
        if ($file === null)
        {
            $song->setCoverFile($this->getParameter('default_cover'));
        }
        else
        {
            $fileName = $this
                ->get('app.file_uploader')
                ->setDir($this->get('kernel')->getRootDir()."/../web".$this->getParameter('covers_directory'))
                ->upload($file);

            $song->setCoverFile($fileName);
        }

        $song->setUploader($user);
        $song->setUploaderID($user->getId());
        $user->addSong($song);

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

        return $this->redirectToRoute('song_view', [
            'id' => $song->getId()
        ]);
    }

    return $this->render('song/upload.html.twig', [
        'form' => $form->createView()
    ]);
}

SoundType - Form

public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder
        ->add('file', FileType::class)
        ->add('coverFile', FileType::class, [
            'required' => false
        ])
        ->add('songName', TextType::class)
        ->add('songAuthor', TextType::class);
}

回答1:

Here is the answer:

{
      $builder
          ->add('file', FileType::class, array('data_class' => null))
          ->add('coverFile', FileType::class, array('data_class' => null))
          ->add('coverFile', FileType::class, array('data_class' => null,'required' => false))
          ->add('songName', TextType::class)
          ->add('songAuthor', TextType::class);
  }

回答2:

/**
 * @ORM\Column(type="string")
 *
 * @Assert\NotBlank(message="Please, upload the song as a MP3 file.")
 * @Assert\File(mimeTypes={ "audio/mpeg", "audio/wav", "audio/x-wav", "application/octet-stream" })
 */
private $file;

You tell doctrine that you want to store a string, but you render an upload button in the form which send you a physic file which you do not want to store in your database at all. Instead you want to move the file from a temporary directory to your upload directory, and you want to remember the name of the file into the database wherefore you need this property which is a string.

Best way is to follow this page

来源：https://stackoverflow.com/questions/40983353/the-forms-view-data-is-expected-to-be-an-instance-of-class-but-is-an-stri

标签

php

symfony

data-class