Displaying “application-specific” validation errors in web UI using Thymeleaf's “fields.hasErrors”

Question

I use Spring MVC together with Thymeleaf. I have an issue with Thymeleaf fields.hasErrors which is as follows:

When a Bean Validation constraint error is raised (such as a @NotNull constraint), the following use of fields.hasErrors works perfectly:

<span class="help-inline" th:if="${#fields.hasErrors('member.email')}" th:text="#{message_form.validation.email}"></span>

An error message is displayed OK next to the email field.

However, when an "application-specific" error (as opposed to Bean Validation constraint error) is raised by my code (see code from controller below),

// FROM SPRING MVC CONTROLLER
if (!registrationService.isEmailAvailable(registrationInfo.getMember().getEmail())) {
    bindingResult.addError(new ObjectError("member.email", "email already used")); // TODO i18n
}

The th:if="${#fields.hasErrors('member.email')}" does not evaluate to true and no error message is displayed....

The only way I have found to display those "application-specific" errors is to include the following underneath the form:

<div id="errors" class="alert alert-error">
    <ul th:if="${#fields.hasErrors('*')}">
        <li th:each="err : ${#fields.errors('*')}" th:text="${err}"></li>
    </ul>
</div>

Then, it will display "email already used" as a list item.

Can anyone please clarify the behavior of th:if="${#fields.hasErrors('member.email')}" and especially tell me why it will evaluate to false in the case of "application specific" errors?

Answer 1

I found the solution to my isue: My problem comes from an incorrect usage of the Spring API.

I should be using a FieldError instead of an ObjectError.

So changing from:

   //FROM SPRING MVC CONTROLLER
    if (!registrationService.isEmailAvailable(registrationInfo.getMember().getEmail())) {
        bindingResult.addError(new ObjectError("member.email", "email already used"));//TODO i18n
    }

to

   //FROM SPRING MVC CONTROLLER
    if (!registrationService.isEmailAvailable(registrationInfo.getMember().getEmail())) {
        bindingResult.addError(new FieldError("registrationInfo","member.email", "email already used"));//TODO i18n
    }

solved the problem.