イメージを含む作業エンティティReferences.phpがありますが、Symfony2 でこの参照に保存されている古いイメージを削除し (存在する場合)、新しいイメージを作成する方法がわかりません。現在のイメージは削除されていないため、新しいイメージを作成し、image_pathこのエンティティに新しいセットを作成しただけです。メソッドで削除しようとしましたpreUploadが、現在のファイルをに設定してNULLから何も設定しません(エラーが発生しました-ファイルを選択する必要があります)
<?php
namespace Acme\ReferenceBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\HttpFoundation\File\UploadedFile;
/**
 * @ORM\Entity(repositoryClass="Acme\ReferenceBundle\Entity\ReferenceRepository")
 * @ORM\Table(name="`references`") 
 * @ORM\HasLifecycleCallbacks 
 */
class Reference
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;              
    /**
     * @ORM\Column(type="string", length=200)    
     * @Assert\NotBlank(
     *      message = "Name cannot be blank"      
     * )    
     * @Assert\Length(
     *      min = "3",
     *      minMessage = "Name is too short"         
     * )     
     */     
    private $name;
    /**
     * @ORM\Column(type="string", length=200)    
     * @Assert\NotBlank(
     *      message = "Description cannot be blank"      
     * )    
     * @Assert\Length(
     *      min = "3",
     *      minMessage = "Description is too short"         
     * )     
     */     
    private $description;
    /**
     * @ORM\Column(type="string", length=200)
     * @Assert\Url(
     *      message = "URL is not valid"
     * )          
     */     
    private $url;
    /**
     * @ORM\ManyToMany(targetEntity="Material", inversedBy="references")
     * @Assert\Count(min = 1, minMessage = "Choose any material") 
     */
    private $materials;
    /**
     * @ORM\Column(type="text", length=255, nullable=false)
     * @Assert\NotNull(
     *      message = "You have to choose a file"
     * )     
     */
    private $image_path;
    /**
     * @Assert\File(
     *     maxSize = "5M",
     *     mimeTypes = {"image/jpeg", "image/gif", "image/png", "image/tiff"},
     *     maxSizeMessage = "Max size of file is 5MB.",
     *     mimeTypesMessage = "There are only allowed jpeg, gif, png and tiff images"
     * )
     */
    private $file;                  
    /**
     * Get id
     *
     * @return integer 
     */
    public function getId()
    {
        return $this->id;
    }
    /**
     * Set name
     *
     * @param string $name
     * @return Reference
     */
    public function setName($name)
    {
        $this->name = $name;
        return $this;
    }
    /**
     * Get name
     *
     * @return string 
     */
    public function getName()
    {
        return $this->name;
    }
    /**
     * Set description
     *
     * @param string $description
     * @return Reference
     */
    public function setDescription($description)
    {
        $this->description = $description;
        return $this;
    }
    /**
     * Get description
     *
     * @return string 
     */
    public function getDescription()
    {
        return $this->description;
    }
    /**
     * Set url
     *
     * @param string $url
     * @return Reference
     */
    public function setUrl($url)
    {
        $this->url = $url;
        return $this;
    }
    /**
     * Get url
     *
     * @return string 
     */
    public function getUrl()
    {
        return $this->url;
    }
    /**
     * Set materials
     *
     * @param string $materials
     * @return Reference
     */
    public function setMaterials($materials)
    {
        $this->materials = $materials;
        return $this;
    }
    /**
     * Get materials
     *
     * @return string 
     */
    public function getMaterials()
    {
        return $this->materials;
    }
    /**
     * Set image_path
     *
     * @param string $imagePath
     * @return Reference
     */
    public function setImagePath($imagePath)
    {
        $this->image_path = $imagePath;
        return $this;
    }
    /**
     * Get image_path
     *
     * @return string 
     */
    public function getImagePath()
    {
        return $this->image_path;
    }
    public function setFile(UploadedFile $file = null)
    {
        $this->file = $file;
    }
    /**
     * Get file.
     *
     * @return UploadedFile
     */
    public function getFile()
    {
        return $this->file;
    }
    /**
    * Called before saving the entity
    * 
    * @ORM\PrePersist()
    * @ORM\PreUpdate()
    */
    public function preUpload()
    {   
        $oldImage = $this->image_path;
        $oldImagePath = $this->getUploadRootDir().'/'.$oldImage;
        if (null !== $this->file) {
            if($oldImage && file_exists($oldImagePath)) unlink($oldImagePath); // not working correctly
            $filename = sha1(uniqid(mt_rand(), true));
            $this->image_path = $filename.'.'.$this->file->guessExtension();
        }
    }
    /**
    * Called before entity removal
    *
    * @ORM\PostRemove()
    */
    public function removeUpload()
    {
        if ($file = $this->getAbsolutePath()) {
            unlink($file);
        }
    }
    /**
    * Called after entity persistence
    *
    * @ORM\PostPersist()
    * @ORM\PostUpdate()
    */
    public function upload()
    {
        // the file property can be empty if the field is not required
        if (null === $this->file) {
            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->file->move(
            $this->getUploadRootDir(),
            $this->image_path
        );
        // set the path property to the filename where you've saved the file
        $this->image_path = $this->file->getClientOriginalName();
        // clean up the file property as you won't need it anymore
        $this->file = null;
    }
    protected function getAbsolutePath()
    {
        return null === $this->image_path
            ? null
            : $this->getUploadRootDir().'/'.$this->image_path;
    }
    protected function getUploadRootDir()
    {
        // the absolute directory path where uploaded
        // documents should be saved
        return __DIR__.'/../../../../'.$this->getUploadDir();
    }
    protected function getUploadDir()
    {
        // get rid of the __DIR__ so it doesn't screw up
        // when displaying uploaded doc/image in the view.
        return 'uploads/references';
    }
    public function getWebPath()
    {
        return $this->getUploadDir().'/'.$this->image_path;
    }
    /**
     * Constructor
     */
    public function __construct()
    {
        $this->materials = new \Doctrine\Common\Collections\ArrayCollection();
    }
    /**
     * Add materials
     *
     * @param \Acme\ReferenceBundle\Entity\Material $materials
     * @return Reference
     */
    public function addMaterial(\Acme\ReferenceBundle\Entity\Material $materials)
    {
        $this->materials[] = $materials;
        return $this;
    }
    /**
     * Remove materials
     *
     * @param \Acme\ReferenceBundle\Entity\Material $materials
     */
    public function removeMaterial(\Acme\ReferenceBundle\Entity\Material $materials)
    {
        $this->materials->removeElement($materials);
    }
}
何か案が?