将文件上载添加到Symfony2表单会抛出一个“；“未找到实体”；并且会话为活动错误

我有一个Symfony2表单，我想在其中添加一个文件上传对话框

根据Symfony文件(http://symfony.com/doc/2.0/cookbook/doctrine/file_uploads.html)，我创建了一个文档类：

<?php

namespace Acme\AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\HttpFoundation\File\UploadedFile;
use Symfony\Component\Validator\Constraints as Assert;

/**
 * @ORM\Entity
 * @ORM\HasLifecycleCallbacks
 */
class Document
{

    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    public $id;

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

    /**
     * @Assert\File(maxSize="6000000")
     */
    public $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/documents';
    }

    /**
     * @ORM\PrePersist()
     * @ORM\PreUpdate()
     */
    public function preUpload()
    {
        if (null !== $this->file) {
            $this->path = sha1(uniqid(mt_rand(), true)).'.'.$this->file->guessExtension();
        }
    }

    /**
     * @ORM\PostPersist()
     * @ORM\PostUpdate()
     */
    public function upload()
    {
        if (null === $this->file) {
            return;
        }

        $this->file->move($this->getUploadRootDir(), $this->path);

        unset($this->file);
    }

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

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

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

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

但是页面标题是“找不到实体。（500内部服务器错误）”

有人能发现它找不到的实体吗？或者这就是问题所在

---

我用谷歌搜索了一下，检查了php.ini中session.auto_start是否设置为0，我已经清除了所有会话和缓存。。。我被难住了

原来我收到这个奇怪的会话错误消息是因为我的nginx配置中有一个错误页面定义

---

通过更正“我的实体”中的一些错误，解决了“未找到实体”问题。Symfony开发者栏为我提供了足够的信息来追踪问题。

如果没有更多信息，很难说出哪里出了问题。我建议您直接转到

classes.php

并导航到第421行。您可能会得到一些提示，实体是您的问题还是其他问题……我也有同样的问题，无法找到未找到的实体。我还检查了开发人员栏，看不出哪个实体失败了。你能不能提供一些信息，如何处理找不到的实体。对不起，贝特里斯特，我上面发布的信息是我能提供的全部。我在调试栏中查看了我的实体，其中一些实体显示了错误。解决错误后，EntityNotFound错误消失。也许您应该创建一个新的SO问题，详细说明您的问题，并将其发布在irc.freenode.net上的#symfony room中，让一些symfony专家来看看。非常感谢您的回复和建议。

<?php

namespace Acme\AppBundle\Form;

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

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

        public function setDefaultOptions(OptionsResolverInterface $resolver)
        {
            $resolver->setDefaults(array(
                    'data_class' => 'Acme\AppBundle\Entity\Document',
            ));
        }

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

<?php

namespace Acme\AppBundle\Entity\Profile;

use Doctrine\ORM\Mapping as ORM;
use Acme\AppBundle\Entity\jDocument;
use Symfony\Component\Validator\Constraints as Assert;

/**
 * @ORM\Entity
 * @ORM\Table(name="UserProfile")
 */
class UserProfile extends GenericProfile
{

    //... Other entity params

    /**
     * @ORM\OneToOne(cascade={"persist", "remove"}, targetEntity="Acme\AppBundle\Entity\Document")
     * @ORM\JoinColumn(name="picture_id", referencedColumnName="id", onDelete="set null")
     */
    protected $picture;

    /**
     * Set picture
     *
     * @param Acme\AppBundle\Entity\Document $picture
     */
   //\Acme\AppBundle\Entity\Document  
    public function setPicture($picture)
    {
        $this->picture = $picture;
    }

    /**
     * Get picture
     *
     * @return Acme\AppBundle\Entity\Document
     */
    public function getPicture()
    {
        return $this->picture;
    }

    //... Other entity getters and setters

}

ErrorException: Warning: ini_set(): A session is active. You cannot change the session module's ini settings at this time in /var/www/wolseley-integrated-services/builds/dev/app/cache/prod/classes.php line 421