如何在不使用表单taglib的情况下访问JSP中的Spring 3 MVC验证器结果

Question

I have a simple Spring 3 MVC form using jsp taglibs. I need to add a class based on whether a field within the form has any errors associated with it or not. Here is a snipet of my HTML:

<div class="control-group error"> <!-- HERE: binding.hasErrors() ? "error" : "" -->
    <form:label path="username" cssClass="control-label">User Name</form:label>
    <div class="controls">
        <form:input path="username" cssClass="span3"/>
        <form:errors path="username" cssClass="help-inline" />
    </div>
</div>

So on the first line the class attribute has two classes "control-group" and "error". I need to add error class only if that field has an error associated with it. I know the WebDataBinder is included in the page somehow, but I don't know how to access it. Essentially I just want to execute some good old fashion <%= binding.hasError() ? "error" : "" %>, but how do I get access to the binder in the page?

Answer 1

Did you try <spring:hasBindErrors> tag (I don't understand what you mean writing "without using form taglib")?

<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>

<spring:hasBindErrors name="yourCommandName">
  <c:if test="${errors.hasFieldErrors('username')}">
    <c:set var="errorClass" value="error" />
  </c:if>
</spring:hasBindErrors>

<div class="control-group <c:out value='${errorClass}' />">

Edit after comments:

Inside <spring:hasBindErrors> tag there is errors variable (see Errors interface ) bound to actual binding errors. You can check if field has errors via errors.hasFieldErrors(fieldName) .

---

_{And really obscure way to get field errors without any tag is requestScope['org.springframework.validation.BindingResult.yourCommandName'].hasFieldErrors('username') ...}

Answer 2

While this is a little more obscure I think it's simpler because it's a single line which is what it would be if I were just using scriplets like any sane Java dev should. Taglibs need to die die die die, then die some more. They are horrible and I can't believe Java devs still think they actually help and not waste our utter time. PHP developers laugh at us when we use those things.

<div class="control-group ${requestScope['org.springframework.validation.BindingResult.user'].hasFieldErrors('firstName') ? 'error' : ''}">

Answer 3

There is a better way to get the error message

<spring:hasBindErrors name="yourCommandName">
    ${errors.hasFieldErrors('userId') ? errors.getFieldError('userId').defaultMessage : ''}
</spring:hasBindErrors>

And one liner

 ${requestScope['org.springframework.validation.BindingResult.user'].hasFieldErrors('emailId') ? requestScope['org.springframework.validation.BindingResult.user'].getFieldError('emailId').defaultMessage : ''}