表单验证后的Playframework IllegalStateException

不幸的是,当我提交表单并且验证失败时,我得到一个可能是游戏错误的IllegalStateException(但我想确认).

请在下面找到相关的代码摘录和问题描述(为了清晰起见,只有相关部分)

部分控制器代码(接收表单提交)

public static Result save() {
    Form<UserForm> userForm = form(UserForm.class).bindFromRequest();
    if (userForm.hasErrors()) {
        return badRequest(createForm.render(userForm));
    }
    UserForm user = userForm.get();

验证器声明为

public class FieldMatchValidator extends Validator<Object>
    implements ConstraintValidator<FieldMatch,Object>

验证注释声明为

@Target({TYPE,ANNOTATION_TYPE})
@Retention(RUNTIME)
@Constraint(validatedBy = FieldMatchValidator.class)
@play.data.Form.Display(name="constraint.fieldmatch")
public @interface FieldMatch {

    String message() default FieldMatchValidator.message;
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};

提交表单我收到错误

Caused by: java.lang.IllegalStateException: No value
    at play.libs.F$None.get(F.java:217) ~[play_2.9.1.jar:2.0.1]
    at play.data.Form.get(Form.java:363) ~[play_2.9.1.jar:2.0.1]
    at controllers.UsersController.save(UsersController.java:40) ~[classes/:2.0.1]
    at Routes$$anonfun$routes$1$$anonfun$apply$25$$anonfun$apply$26.apply(routes_routing.scala:189) ~[classes/:na]
    at Routes$$anonfun$routes$1$$anonfun$apply$25$$anonfun$apply$26.apply(routes_routing.scala:189) ~[classes/:na]
    at play.core.Router$HandlerInvoker$$anon$4$$anon$1.invocation(Router.scala:1086) ~[play_2.9.1.jar:2.0.1]

提到的UsersController的行是调用UserForm user = userForm.get();

试图了解问题所在,我发现有问题的代码可能在play的Form.java中.

Form绑定(Map data,String … allowedFields)包含：

if(result.hasErrors()) {

    for(FieldError error: result.getFieldErrors()) {
    ...
    }
return new Form(rootName,backedType,data,errors,None());
}

并且hasErrors()是

public boolean hasErrors() {
    return !errors.isEmpty();
}

结果是result.hasErrors()返回true(因为在类级别定义的验证器失败),但构建的错误列表仍为空(result.getFieldErrors()返回一个空列表).

因此,Form.hasErrors()返回false但Form.get()失败.

我错过了什么或者它实际上是一个错误？

感谢致敬,