Symfony / VichUploaderBundle图片上传

I'm trying to upload thumbnail to Post entity using Image entity. I've installed VichUploaderBundle. Image upload runs without an error but when I look at db in path field i have something like this:

/private/var/folders/6p/brq75f3j1dq2vj6sk21bgw5h0000gn/T/phpyJra9T

instead of filename. Here are my files: configm.yml

vich_uploader:
    db_driver: orm
    mappings:
        gallery_image:
            uri_prefix:         /uploads/gallery
            upload_destination: %kernel.root_dir%/../web/uploads/gallery
            inject_on_load:     false
            delete_on_update:   true
            delete_on_remove:   true

Image.php:

/**
 * @ORM\Column(type="string", length=255, nullable=false)
 */
private $path;

/**
 *
 * @Assert\File(
 *     maxSize = "5M",
 *     mimeTypes = {"image/jpeg", "image/gif", "image/png", "image/tiff"},
 *     maxSizeMessage = "The maxmimum allowed file size is 5MB.",
 *     mimeTypesMessage = "Only the filetypes image are allowed."
 * )
 * @Vich\UploadableField(mapping="gallery_image", fileNameProperty="path")
 */
private $file;


/**
 * Get id
 *
 * @return integer
 */
public function getId()
{
    return $this->id;
}

public function setFile(File $image = null)
{
    $this->file = $image;
    return $this;
}
/**
 * @return File
 */
public function getFile()
{
    return $this->file;
}

PostType:

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('title')
            ->add('body', TextareaType::class, array('required'=>false))
            ->add('tags', TextType::class, array('required'=> false))
            ->add('thumbnail', ImageType::class, ['required' => false])
        ;
    }

ImageType:

public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder
        ->add('path', FileType::class, ['label'=>false, 'data_class' => null])
    ;
}

I don't have any idea where is the problem, please help me.