How can I save custom variables into the request in a Struts application in Java?

Question

I'm using Struts 1.2 and J2EE 1.4. I'm pretty new to Struts and Java so hopefully there is a simple solution for my problem. I have a page set up like this:

<div class="success">
    HTML for success
</div>
<div class="error">
    <p>We are experiencing technical difficulties at this time. Please try your request again later.</p>
</div>
<div id="contact-form-block">
    <html:form action="/reg" id="contactform">

    <br /><html:text property="firstName"/><html:errors property="firstName"/>
        <p><input type="image" src="images/reset_btn.png" id="reset" name="reset" alt="Reset" /><input type="image" src="images/submit_btn.png" id="submit" name="submit" alt="Submit" /></p>
    </div>

</html:form>
</div>

Originally the success, error and contact us divs are all hidden. I have the contact form show up on click in a modal dialog box like this:

$('.success, .error, .success_header, .error_header').hide();
$('form#contactForm').show();

So, in my Action, I want to be able to send everything back to the same input forward regardless of whether there were validation errors or not. BUT I want to have a check on the jsp page in jQuery to check to see which dialog should be displayed:

1. The Success dialog OR
2. The contact-us dialog with the errors

Here is my action:

if ("reg".equalsIgnoreCase(contactUsForm.getAction())) {            

        ActionMessages errors = getErrors(request);

        errors = validate(contactUsForm);

        if (errors.isEmpty()) {

           //Save some variable to the request/response to say that registration was successful

        } else {
             //save something to say that registration was not successful
            saveErrors(request, errors);
        }
    }
    return actionForward;

Is there a way to set a variable in the Action that can be retrieved in the jsp page after the ActionForward is called. Preferably accessible by jQuery in the $(document).ready function?

Answer 1

You would use normal Struts and/or servlet spec mechanisms.

You could just check to see if there are errors or not; they're stored in the request under the "org.apache.struts.action.ERROR" key; you don't need to add anything in particular, but if you really want to, you may.

I prefer non-form data to be stored as a request attribute:

request.setAttribute("haveErrors", true); // Or false, obviously.

You then need to get the data out of the request in your JSP, and interpreted as JavaScript:

$(function() {
    // Use normal JSP EL; haveErrors should display as a bare string, 
    // which is valid JS. Can modify as necessary if need be.
    var haveErrors = ${haveErrors};
});

Answer 2

I'm not sure if I understood the question right but if you mean, is there a way for you to pass variables from within the Action class to the JSP, then yes there is.

In the Action class before the return statement set a variable to the request context like below:

 request.setAttribute("successfulRegistration", "true");

Always remember that the JSP gets compiled at the server side and then any HTML added to the response before it reaches the browser to be rendered or the javascript processed. So,

In the JSP as an example:

<script type="text/javascript>
var success = <% (String) request.getAttribute("successfulRegistration"); %>
</script>

of since the variable is a String it could be shortened to:

<script type="text/javascript">
var success = <%=request.getAttribute("successfulRegistration")%>
</script>

The success variable in javascript would already have its variable assigned at the JSP compilation time on the server side before it reaches the browser.

JSPs can share data with the Action classes through the request, session and application contexts.

Request - request.getAttribute(...)
Session - request.getSession().getAttribute(...)
Application - application.getAttribute(...)

Similarly in Action class these can be set - application context is accessed by the ServletContext class.