表单无效时丢失图像

Question

我很困惑。我将图像保存到临时文件夹。当表单未在提交时验证时，为什么表单会丢失图像名称？

继承人我所拥有的：

if(CUploadedFile::getInstance($model, 'product_image') !==null)
{
$product_image=CUploadedFile::getInstance($model,'product_image');
$f_product_image = "{$impdate}{$random6}{$product_image}"; 
$model->product_image = $f_product_image;
    if($session['image0']&&file_exists($thumb.'thumb_'.$session['image0'])){
    $old_name = $session['image0'];
    unlink($url.$old_name);
    unlink($thumb.'thumb_'.$old_name);
    }else $session['image0']=$f_product_image;
}
else $model->product_image = $session['image0'];