Forms 在Symfony 2中嵌入表单集合并添加多个文件

我在这里遵循教程：

该示例有效，但当我尝试添加filetype字段时，出现以下错误：

Error: Call to a member function move() on a non-object

不知道为什么。我可以动态添加任意多个fieldType字段，但问题在于上面的错误

这是我的密码：

TagType.php

namespace Bundle\MyBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class TagType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        //$builder->add('name');
        $builder->add('file','file',array('label' => 'Load file'));
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'Bundle\MyBundle\Entity\Tag',
        ));
    }

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

TaskType.php

namespace Bundle\MyBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class TaskType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('description');

        $builder->add('file', 'collection', array(
            'type' => new TagType(),
            'allow_add'    => true,
        ));
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'Bundle\MyBundle\Entity\Task',
        ));
    }

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

Task.php

/**
 * Task
 */
class Task
{   
    /**
     * @var string
     */
    protected $description;

    /**
     * @var string
     */
    protected $tags;

    /**
     * @var integer
     */

    /**
     * @var string
     */
    protected $file;

    /**
     * @var string
     */
    protected $path;

    protected $id;

    public function __construct()
    {
        $this->tags = new ArrayCollection();
    }



    /**
     * Set description
     *
     * @param string $description
     * @return Task
     */
    public function setDescription($description)
    {
        $this->description = $description;
    }

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

    /**
     * Set tags
     *
     * @param string $tags
     * @return Task
     */
    public function setTags($tags)
    {
        $this->tags = $tags;
    }

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



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

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



    /**
     * Set file
     *
     * @param string $file
     * @return Task
     */
    public function setFile($file)
    {
        $this->file = $file;

        return $this;
    }

    /**
     * Get file
     *
     * @return string 
     */
    public function getFile()
    {
        return $this->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()
    {   
        $user_folder = $this->getId();
        // get rid of the __DIR__ so it doesn't screw up
        // when displaying uploaded doc/image in the view.
        return 'uploads/task/';
    }

    public function upload()
    {
        // the file property can be empty if the field is not required
        if (null === $this->getFile()) {
            return;
        }

        // use the original file name here but you should
        // sanitize it at least to avoid any security issues

        // move takes the target directory and then the
        // target filename to move to
        $this->getFile()->move(
            $this->getUploadRootDir(),
            $this->getFile()->getClientOriginalName()
        );

        // set the path property to the filename where you've saved the file
        return $this->path = $this->getFile()->getClientOriginalName();



        // clean up the file property as you won't need it anymore
        $this->file = null;
    }
}

Tag.php

class Tag
{   
    /**
     * @var string
     */
    private $file;

    /**
     * @var string
     */
    private $path;

    /**
     * @var string
     */
    public $name;

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

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



    /**
     * Set file
     *
     * @param string $file
     * @return Task
     */
    public function setFile($file)
    {
        $this->file = $file;

        return $this;
    }

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

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

        return $this;
    }

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

    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()
    {   
        $user_folder = $this->getId();
        // get rid of the __DIR__ so it doesn't screw up
        // when displaying uploaded doc/image in the view.
        return 'uploads/task/';
    }

    public function upload()
    {
        // the file property can be empty if the field is not required
        if (null === $this->getFile()) {
            return;
        }

        // use the original file name here but you should
        // sanitize it at least to avoid any security issues

        // move takes the target directory and then the
        // target filename to move to
        $this->getFile()->move(
            $this->getUploadRootDir(),
            $this->getFile()->getClientOriginalName()
        );

        // set the path property to the filename where you've saved the file
        return $this->path = $this->getFile()->getClientOriginalName();



        // clean up the file property as you won't need it anymore
        $this->file = null;
    }
}

控制器：

$task = new Task();

$form = $this->createForm(new TaskType(), $task);
$form->add('submit', 'submit', array('label' => 'Create'));

$form->handleRequest($request);


if ($form->isValid()) {



        $em = $this->getDoctrine()->getManager();
        $task->upload();
        //$task->setTags($val);
        $em->persist($task);
        $em->flush();
        $em->clear();

}