symfony2文件因表单错误而丢失

当我的上传表单在验证中遇到错误,并将用户发送回带有错误消息的表单时,它会丢失选择上传的文件,但如果我var_dump我的$entity->文件我可以看到它有该文件. ..

//if form is valid,do some stuff... if not:
    else {

        //var_dump($entity->file); //This works,I get my file
        //die;

        //Get and check the folder chosen as parent
        $entity->setFolder( $this->checkFolderId($request->request->get('folder')) ); //will cause die() if folder doesn't belong to this company

        $folders = $this->getFolders();

        return $this->render('BizTVMediaManagementBundle:Image:new.html.twig',array(
            'entity' => $entity,'form'   => $form->createView(),'folders' => $folders,'fileExists' => $fileExists,));

    }

将其放入树枝视图后,文件字段中没有任何内容.

这是我的实体……

<?php

namespace BizTVMediaManagementBundleEntity;

use DoctrineORMMapping as ORM;
use SymfonyComponentValidatorConstraints as Assert;

/**
 * BizTVMediaManagementBundleEntityImage
 *
 * @ORMTable(name="image")
 * @ORMEntity
 * @ORMHasLifecycleCallbacks
 */
class Image
{
    /**
     * @var integer $id
     *
     * @ORMColumn(name="id",type="integer")
     * @ORMId
     * @ORMGeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string $name

     *
     * @ORMColumn(name="name",type="string",length=255)
     * @AssertNotBlank
     */
    private $name;

    /**
     * @var integer $width
     *
     * @ORMColumn(name="width",type="integer")
     */
    private $width;

    /**
     * @var integer $height
     *
     * @ORMColumn(name="height",type="integer")
     */
    private $height;

    /**
     * @ORMColumn(type="string",length=255,nullable=true)
     */
    private $path;

    /**
    * @var object BizTVBackendBundleEntitycompany
    *  
    * @ORMManyToOne(targetEntity="BizTVBackendBundleEntitycompany")
    * @ORMJoinColumn(name="company",referencedColumnName="id",nullable=false)
    */
    protected $company;     

    /**
    * @var object BizTVMediaManagementBundleEntityFolder
    *  
    * @ORMManyToOne(targetEntity="BizTVMediaManagementBundleEntityFolder")
    * @ORMJoinColumn(name="folder",nullable=true)
    */
    protected $folder;


    /**
     * @AssertFile(maxSize="6000000")
     */
     public $file;


    /**
     * @ORMPrePersist()
     * @ORMPreUpdate()
     */
    public function preUpload()
    {
        if (null !== $this->file) {
            // do whatever you want to generate a unique name
            $this->path = sha1(uniqid(mt_rand(),true)).'.'.$this->file->guessExtension();
        }
    }

    /**
     * @ORMPostPersist()
     * @ORMPostUpdate()
     */
    public function upload()
    {
        if (null === $this->file) {
            return;
        }

        // if there is an error when moving the file,an exception will
        // be automatically thrown by move(). This will properly prevent
        // the entity from being persisted to the database on error
        $this->file->move($this->getUploadRootDir(),$this->path);

        unset($this->file);
    }

    /**
     * @ORMPostRemove()
     */
    public function removeUpload()
    {
        if ($file = $this->getAbsolutePath()) {
            unlink($file);
        }
    }    

    public function getAbsolutePath()
    {
        return null === $this->path ? null : $this->getUploadRootDir().'/'.$this->path;
    }

    public function getWebPath()
    {
        return null === $this->path ? null : $this->getUploadDir().'/'.$this->path;
    }

    protected function getUploadRootDir()
    {
        // the absolute directory path where uploaded documents should be saved
        return __DIR__.'/../../../../web/'.$this->getUploadDir();

    }

    protected function getUploadDir()
    {
        // get rid of the __DIR__ so it doesn't screw when displaying uploaded doc/image in the view.
        return 'uploads/images';
    }


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

    /**
     * Set name
     *
     * @param string $name
     */
    public function setName($name)
    {
        $this->name = $name;
    }

    /**
     * Get name
     *
     * @return string 
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * Set width
     *
     * @param integer $width
     */
    public function setWidth($width)
    {
        $this->width = $width;
    }

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

    /**
     * Set height
     *
     * @param integer $height
     */
    public function setHeight($height)
    {
        $this->height = $height;
    }

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

    /**
     * Set path
     *
     * @param string $path
     */
    public function setPath($path)
    {
        $this->path = $path;
    }

    /**
     * Get path
     *
     * @return string 
     */
    public function getPath()
    {
        return $this->path;
    }

    /**
     * Set company
     *
     * @param BizTVBackendBundleEntitycompany $company
     */
    public function setCompany(BizTVBackendBundleEntitycompany $company)
    {
        $this->company = $company;
    }

    /**
     * Get company
     *
     * @return BizTVBackendBundleEntitycompany 
     */
    public function getCompany()
    {
        return $this->company;
    }

    /**
     * Set folder
     *
     * @param BizTVMediaManagementBundleEntityFolder $folder
     */
    public function setFolder(BizTVMediaManagementBundleEntityFolder $folder = NULL)
    {
        $this->folder = $folder;
    }

    /**
     * Get folder
     *
     * @return BizTVMediaManagementBundleEntityFolder 
     */
    public function getFolder()
    {
        return $this->folder;
    }


}

形式：

<?php

namespace BizTVMediaManagementBundleForm;

use SymfonyComponentFormAbstractType;
use SymfonyComponentFormFormBuilder;

class ImageType extends AbstractType
{
    function __construct($createAction=0) {
        $this->createAction = $createAction;    
    }   

    public function buildForm(FormBuilder $builder,array $options)
    {

        $createAction = $this->createAction;

        if ($createAction) {        
            $builder
                ->add('file')
            ;
        }

        $builder
            ->add('name','text',array('label' => 'Namn'))
        ;
    }

    public function getName()
    {
        return 'biztv_mediamanagementbundle_imagetype';
    }
}