如何从验证器发送消息到Thymeleaf中的表单

Question

我从验证器发送消息到查看时遇到问题。当我调试验证器时，返回错误消息，但我不知道如何在视图中显示。我尝试了其他方式来验证表单，但始终不显示来自验证器的消息。

SignConfiguration类

@RequestMapping(value = "/signup", method = RequestMethod.POST)
public ModelAndView createUser(@ModelAttribute("user") @Validated User user, BindingResult bindingResult) {
    ModelAndView model = new ModelAndView();

    model.addObject("user", user);

    if (bindingResult.hasErrors()) {
        signupValidation.validate(user,bindingResult);
        model.setViewName("view/signup");
    } else {
        userService.saveUser(user);
        model.addObject("msg", "Correct registration!");
        model.addObject("user", new User());
        model.setViewName("view/signup");
    }

    return model;
}

SignupValidator类

public class SignupValidation implements Validator {

@Override
public boolean supports(Class<?> aClass) {
    return User.class.equals(aClass);
}

@Override
public void validate(Object o, Errors errors) {

    ValidationUtils.rejectIfEmptyOrWhitespace(errors,"firstname", "signup.error.blank.field");
    ValidationUtils.rejectIfEmptyOrWhitespace(errors,"lastname", "signup.error.blank.field");
    ValidationUtils.rejectIfEmptyOrWhitespace(errors,"email", "signup.error.blank.field");
    ValidationUtils.rejectIfEmptyOrWhitespace(errors,"password", "signup.error.blank.field");

}

signup.html

<div class="popup-window">
<div class="popup-content">
    <form class="form-input" role="form" method="POST" th:action="@{/signup}" th:object="${user}">
        <a th:href="@{/}" class="close" id="close-sign-up">+</a>

        <div class="user-input">
            <label for="email" th:text="|#{signup.email.placeholder}:|"></label>
            <input type="text" th:field="*{email}" id="email" name="email"
                   th:placeholder="#{signup.email.placeholder}">
            <div class="error-email" role="alert" th:if="${#fields.hasErrors('email')}" th:error="*{email}"
                ></div>
        </div>

        <div class="user-input">
            <div class="correct-register" role="alert" th:if="${msg}" th:text="${msg}"></div>
            <button type="submit" th:text="#{welcome.signup}"></button>
        </div>

    </form>
</div>