如何在Symfony 4中将表单中的错误转换为字符串？

composer require symfony/form

// src/Form/ContactFormType.php

namespace App\Form;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\Form\Extension\Core\Type\EmailType;
use Symfony\Component\Form\Extension\Core\Type\TextareaType;

class ContactFormType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('name', TextType::class)
            ->add('email', EmailType::class)
            ->add('message', TextareaType::class);
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            // 配置表单数据类
            'data_class' => ContactFormData::class,
        ]);
    }
}

// src/Controller/ContactController.php

namespace App\Controller;

use App\Form\ContactFormType;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Annotation\Route;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;

class ContactController extends AbstractController
{
    /**
     * @Route("/contact", name="contact")
     */
    public function contact(Request $request)
    {
        $form = $this->createForm(ContactFormType::class);

        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
            // 处理表单提交
            // ...

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

        // 将错误转换为字符串
        $errors = [];
        foreach ($form->getErrors(true) as $error) {
            $errors[] = $error->getMessage();
        }
        $errorString = implode(', ', $errors);

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