从 Symfony2 中的订阅者(表单事件)访问表单字段 [英] Accessing a form field from a subscriber (of a form event) in Symfony2

问题描述

我正在学习如何使用表单事件动态生成表单.我被困在 AddNameFieldSubscriber 的创建上:

I'm following the tutorial How to Dynamically Generate Forms Using Form Events. I'm stuck on the creation of AddNameFieldSubscriber:

$subscriber = new AddNameFieldSubscriber($builder->getFormFactory());

我的问题很简单:FormFactory 如何访问和修改以前由 $builder 创建的任意表单字段?为什么我们要传递 FormFactory 而不是 $builder 本身?

My question is simple: how FormFactory can access and modify an arbitrary form field previously created by the $builder? And why we are passing the FormFactory instead of the $builder itself?

假设我们在 builder 中只有两个字段(name"和price"):

Assuming we have just two fields ("name" and "price") in the builder:

class ProductType extends AbstractType
{
    public function buildForm(FormBuilder $builder, array $options)
    {
        $subscriber = new AddProductTypeSubscriber($builder->getFormFactory());
        $builder->addEventSubscriber($subscriber);

        $builder->add('name');
        $builder->add('price');
    }

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

我想在订阅者中设置required = false(只是一个例子):

I'd like to set required = false (just an example) in the subscriber:

class ProductTypeSubscriber implements EventSubscriberInterface
{
    private $factory;

    public function __construct(FormFactoryInterface $factory)
    {
        $this->factory = $factory;
    }

    public static function getSubscribedEvents()
    {
        return array(FormEvents::PRE_SET_DATA => 'preSetData');
    }

    public function preSetData(DataEvent $event)
    {
        $data = $event->getData();
        $form = $event->getForm();

        if (null === $data) return;

        // Access "name" field and set require = false
    }
}

推荐答案

我可能错了，但我不相信您可以在创建表单后更改其属性.但是，您可以添加到表单中.

I could be wrong about it this, but I don't believe you can change a form's attributes after its been created. However, you can add to the form.

不是在 ProductType::buildForm 中添加 'name' 字段，您可以将其推迟到订阅者:

Instead of adding the 'name' field in ProductType::buildForm, you can defer this to the subscriber:

if (!$data->getId()) {
    $form->add($this->factory->createNamed('text', 'name', null, array('required' => false)));
} else {
    $form->add($this->factory->createNamed('text', 'name'));
}

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