发生验证错误时，Symfony2表单字段未更新

我不能完全解决你的问题，因为在我看来你做这件事的方式不对。数据类实际上只负责保存您的数据，所以您的方法set/getThumbnailData应该看起来像这个

<?php
// ...
private $thumbnailData;
public function setThumbnailData(UploadedFile $thumbnailData) {
    $this->thumbnailData = $thumbnailData;
}
public function getThumbnailData() {
    return $this->thumbnailData;
}

在你的控制器中，你有这样的东西：

<?php
// ...
public function formAction() {
    $form = // ... 
    $form->handleRequest($request);
    if($form->isValid()) {
        $test = $form->getData();
        /* @var $test Test */
        $thumbnailUploader = $this->get('thumbnail_uploader');
        /* @var $thumbnailUploader ThumbnailUploadService */
        $file = $test->getThumbnailData();
        $filename = $file->getClientOriginalName();
        $thumbnailUploader->upload($filename, $file);
        // ...
    }
}

我建议将所有与表单或请求无关的逻辑转移到服务中。在这种情况下，您的服务可以更通用地处理具有给定文件名的任何symfony文件。

<?php
class ThumbnailUploadService {
    /**
     * @param $file Symfony'Component'HttpFoundation'File'File
     *
     */
    public function upload($filename, File $file) {
        // ...
    }
}

还有另一种使用回调的方法。在这里，我给你一个通用类来上传图像并生成缩略图。我希望这对你有用。此类管理在创建更新或删除实体时自动生成的文件。

use Doctrine'ORM'Mapping as ORM;
use Symfony'Bridge'Doctrine'Validator'Constraints as DoctrineAssert;
use Symfony'Component'HttpFoundation'File'UploadedFile;
use Symfony'Component'Validator'Constraints as Assert;
use App'MyBundleBundle'Util'Util;
/**
 * Image
 *
 * @ORM'Table(name="image")
 * @ORM'Entity()
 * @ORM'HasLifecycleCallbacks
 */
class Image
{
    /**
     * @var integer
     *
     * @ORM'Column(name="id", type="integer")
     * @ORM'Id
     * @ORM'GeneratedValue(strategy="AUTO")
     *
     */
    private $id;
    /**
     * @var string
     *
     * @ORM'Column(name="name", type="string")
     * @Assert'NotBlank()
     */
    private $name;

    private $temp;
    /**
     * @ORM'Column(type="string", length=255)
     */
    protected $path;
    /**
     * @Assert'Image(maxSize="5M")
     */
    private $file;
    /**
     * Sets file.
     *
     * @param UploadedFile $file
     */
    public function setFile(UploadedFile $file = null)
    {
        $this->file= $file;
        if (isset($this->path)) {
            $this->temp = $this->path;
            $this->path= null;
        } else {
            $this->path= 'initial';
        }
    }
    /**
     * Get file.
     *
     * @return UploadedFile
     */
    public function getFile()
    {
        return $this->file;
    }
    /**
     * @ORM'PrePersist()
     * @ORM'PreUpdate()
     */
    public function preUpload()
    {
        if (null !== $this->getFile()) {
            // do whatever you want to generate a unique name
            $filename = Util::getSlug($this->name) . uniqid() . '.' . $this->file->guessExtension();
            $this->path = $filename;
        }
    }
    /**
     * @ORM'PostPersist()
     * @ORM'PostUpdate()
     */
    public function upload()
    {
        if (null === $this->getFile()) {
            return;
        }
        $this->getFile()->move($this->getUploadRootDir(), $this->path);
        if (isset($this->temp)) {
            if (file_exists($this->getUploadRootDir() .'/'. $this->temp)) {
                unlink($this->getUploadRootDir() . '/' . $this->temp);
            }
            $this->temp = null;
        }
        $this->file= null;
        //create a dir to save de thumbnails
        if (!file_exists($this->getUploadRootDir() . '/thumbnails')) {
            mkdir($this->getUploadRootDir() . '/thumbnails');
        }
        //call a method in util class to generate the thumbnails
        Util::redim($this->getUploadRootDir() . '/' . $this->path, $this->getUploadRootDir() . '/thumbnails/' . $this->path, 128, 128);
    }
    /**
     * @ORM'PostRemove()
     */
    public function removeUpload()
    {
        //This is to remove the files when the entity is delete
        if ($file = $this->getAbsolutePath()) {
            if (file_exists($file)) {
                unlink($file);
                $thumb = $this->getUploadRootDir() . '/thumbnails/' . $this->getPath();
                if (file_exists($thumb)) {
                    unlink($thumb);
                }
            }
        }
    }
    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()
    {
        return $this->getUploadDir();
    }
    protected function getUploadDir()
    {
        return 'uploads/image/';
    }
    /**
     * Get id
     *
     * @return integer
     */
    public function getId()
    {
        return $this->id;
    }
    /**
     * Set nombre
     *
     * @param string $name
     * @return Image
     */
    public function setName($name)
    {
        $this->name= $name;
        return $this;
    }
    /**
     * Get nombre
     *
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * Set path
     *
     * @param string $path
     * @return Imagen
     */
    public function setPath($path)
    {
        $this->path= $path;
        return $this;
    }
    /**
     * Get path
     *
     * @return string
     */
    public function getPath()
    {
        return $this->path;
    }
    public function __toString()
    {
        return $this->getName();
    }
}