php - 在 Symfony2 Controller 中获取表单值，子级不存在

Question

输入用户名的源代码是这样的:

<input type="text" id="user_username" name="user[username]" >

当我尝试在 Controller 中获取它时，出现此错误:

Child "username" does not exist

Controller :

//.......
if ($request->getMethod() == 'POST') {
        $form->handleRequest($request);
        $i = 0;
        $username = $form["username"]->getData();
        $user= $em->getRepository('UsersBundle:User')->findOneByUsername($username);

//.......
}

这是表单类型

class EleveType extends AbstractType
{
 public function buildForm(FormBuilderInterface $builder, array $options)
   {
    $builder
        ->add('user', new UserType())
        ->add('ecole')
        ->add('niveauscolaire')

    ;
}

Answer 1

替换

$username = $form["username"]->getData();

与

$username = $form["user"]["username"]->getData();