Как загрузить файл используя JMS Serializer?

/**
     * @Type("string")
     * @ORM\Column(type="string", length=255, nullable=true)
     */
    private $file;

$data = array_replace_recursive(
        $request->request->all(),
        $request->files->all()
    );

    $serializer = SerializerBuilder::create()->build();
    $object = $serializer->deserialize(json_encode($data), Answer::class, 'json');

    $em = $this->getDoctrine()->getManager();
    $em->persist($object);
    $em->flush();