Symfony ChoiceType接受JSON请求正文

Question

我正在创建一个Symfony API。我有以下表单类型来接受JSON请求正文：

$builder
        ->add('email', Type\EmailType::class)
        ->add('username', Type\TextType::class)
        ->add('name', Type\TextType::class)
        ->add('plainPassword', Type\RepeatedType::class, array(
            'type' => Type\PasswordType::class,
            'invalid_message' => 'The password fields must match.',
        ))
        ->add('types', Type\ChoiceType::class, [
            'choices' => [
                'Photographer' => 'Photographer',
            ],
            'expanded' => false,
            'multiple' => true
        ])
    ;

我发送JSON Body就像这样：

{"username": "merchant2", "email": "merchant2@gmail.com", "plainPassword": {"first": "gerlie" , "second": "gerlie"}, "name": "merchant2", "types": ["Photographer"]}

表单然后验证它有错误告诉我：

  

您选择的值不是有效选择。

这是由ConstraintValidationExcetption引起的。

请注意，我的实体也是如此断言：

/**
 * @Assert\Choice({"Event Organizer", "Photographer", "Host", "Catering", "Band", "Others"})
 */
private $types;

为什么会这样？

谢谢！