Symfony2 表单生成器自定义未映射字段约束

我只是试图将电子邮件约束添加到下面的未映射字段中，由于某种原因，在控制器操作中它没有拾取它。我还需要做什么吗？

表单类

/**
 * @param FormBuilderInterface $builder
 * @param array $options
 */
public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder->add('name', null, [
        'label' => false,
        'attr' => ['placeholder' => 'Name*']
    ]);
    $builder->add('email', null, [
        'mapped' => false,
        'label' => false,
        'attr' => ['placeholder' => 'Email*'],
        'constraints' => [
            new Email(["message" => "Please enter a valid Email Address"])
        ]
    ]);
}
public function configureOptions(OptionsResolver $resolver)
{
    $resolver->setDefaults(array(
        'data_class' => 'Test'AppBundle'Entity'Feedback',
        'cascade_validation' => true,
        'validation_groups' => function(Form $form)
        {
            $feedback = $form->getData(); /** @var Feedback $feedback */
            if ($feedback->getType() == Feedback::Type_Feedback)
                return Feedback::ValidationGroup_Feedback;
            else if ($feedback->getType() == Feedback::Type_Link)
                return Feedback::ValidationGroup_Link;
            throw new 'Exception("Couldn't generate a valid Validation Group for FeedbackForm.php");
        },
    ));
}
/**
 * @return string
 */
public function getName()
{
    return 'site_feedback_form';
}

控制器操作

public function feedbackSiteSubmitAction(Request $request)
{
    // The form award
    $feedback = new Feedback();
    // Create the form so we can bind send form values to it
    $form = $this->createNewFeedbackForm($feedback);
    // Bind form values
    $form->handleRequest($request);
    // Save
    if ($form->isValid())
    {
        // Add the submission to a member
        $email = $form->get('email')->getData();
        $email = strtolower($email);
        $member = $this->getMemberRepository()->loadByEmail($email);
        if (!$member)
            $member = $this->generateNewPersistedMember($email);
        // Update the mail property
        $member->setReceiveEmail(!$form->get('dontReceiveAlerts')->getData());
        // Add the feedback to the member
        $feedback->setMember($member);
        // Persist the Feedback
        $this->getEntityManager()->persist($feedback);
        // Commit
        $this->getEntityManager()->flush();
        // Response
        return $this->jsonSuccess([
            'html' => $this->renderView('TestAppBundle:Site/partials:feedback_form_success.html.twig', [
                'typeString' => $feedback->getType() == Feedback::Type_Feedback ? "Feedback" : "Resource suggestion"
            ])
        ]);
    }
    // Return errors
    return $this->jsonError($this->getAllFormErrors($form));
}