无法从表单类型的查询构建器函数访问全局变量

我正在尝试在Form类型中将参数设置为查询构建器.我想将impact变量设置为表单字段查询构建器.我impact从表格选项中获得

public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder->add('title');

    $parentPage = $options["parentPage"];
    $impact = $options["impact"];

    if($parentPage != null){
        $builder->add('parent', 'entity', array(
            'class' => "CoreBundle:Page",
            'choices' => array($parentPage)
        ));
    }else{
        $builder->add('parent', 'entity', array(
            'class' => "CoreBundle:Page",
            'query_builder' => function(PageRepository $pr){
                $qb = $pr->createQueryBuilder('p');
                $qb->where("p.fullPath NOT LIKE '/deleted%'");

                $qb->andWhere('p.impact = :impact')
                    ->setParameter('impact', $impact); <-'Undefined variable $impact'

                return $qb;
            },
        ));
    }

为什么这段代码显示错误,它说$impact是未定义的变量.是不是可以从buildForm函数中的任何位置访问的全局变量？

问题是你需要显式指定传递给闭包的变量(也就是query_builder函数):

    $builder->add('parent', 'entity', array(
        'class' => "CoreBundle:Page",
        'query_builder' => function(PageRepository $pr) use ($impact) { // ADD
            $qb = $pr->createQueryBuilder('p');
            $qb->where("p.fullPath NOT LIKE '/deleted%'");

            $qb->andWhere('p.impact = :impact')
                ->setParameter('impact', $impact); <-'Undefined variable $impact'

            return $qb;
        },
    ));

大多数语言不需要这个,但PHP确实如此.参见示例3:http://php.net/manual/en/functions.anonymous.php