将数据传递到集合类型symfony中的子窗体

use Symfony\Component\Form\Extension\Core\Type\CollectionType;
use AppBundle\Form\Type\ChildFormType;

class ParentFormType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('childForms', CollectionType::class, [
                'entry_type' => ChildFormType::class,
                'allow_add' => true,
                'allow_delete' => true,
                'by_reference' => false,
            ]);
    }
}

use AppBundle\Entity\ParentEntity;
use AppBundle\Form\Type\ParentFormType;

class ParentController extends Controller
{
    public function createAction(Request $request)
    {
        $parentEntity = new ParentEntity();
        $form = $this->createForm(ParentFormType::class, $parentEntity);

        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
            // 处理父窗体的数据

            foreach ($parentEntity->getChildForms() as $childForm) {
                // 处理子窗体的数据
            }

            // 保存数据到数据库或执行其他操作

            return $this->redirectToRoute('success');
        }

        return $this->render('parent/create.html.twig', [
            'form' => $form->createView(),
        ]);
    }
}