ValidatorDispatchAction

2003.10.30 - Thank you for struts-resume

Hi Matt,

Kudos on your excellent work on appfuse and struts-resume. Since, I've been using appfuse and struts-resume to gather a basic understanding of struts and "helper" technologies, its time to give back a little.

I ran into the same problem as yourself, as per your email. So, I followed the email thread and wasn't quite happy with the JavaScript solution. So, I conjured a non-JavaScript solution which is posted below. Be aware that my struts understanding is fairly rudimentary and this might be a classic example of too much blending of V into the C from the MVC model.

    /**
     * An overridden validate method which attempts to bypass
     * validation.
     * <div id="caution_overridden_validate" title="Overridden Validate">
     * Due to a bug (or unintended feature) in struts, as
     * explained in
     * <a href="http://nagoya.apache.org/bugzilla/show_bug.cgi?id=16401">this bu
g report</a>
     * its difficult (or impossible) when using the Validator with
     * LookupDispatchAction to bypass validation on a method level
     * without employing JavaScript. I thought it would be nice to have
     * a cancel method with no dependency on JavaScript which was able
     * to bypass validation. Hence, in this class we override the
     * validate method and look for the parameter name (e.g., action) and
     * its value (e.g., Cancel) and if the cancel button was pressed,
     * the call to super.validate is bypassed.
     * <a href="http://www.mail-archive.com/[email protected]/msg60
169.html">Initial report</a>
     * by Matt Raible on struts-user mailing list.
     * Follow up
     * <a href="http://www.mail-archive.com/[email protected]/msg129
62.html">1</a>
     * and
     * <a href="http://www.mail-archive.com/[email protected]/msg129
66.html">2</a>
     * by Brandon Goodin on struts-dev mailing list.
     * </div>
     *
     * @param mapping The <code>ActionMapping</code> used to select this
     * instance
     * @param request The servlet request we are processing
     *
     * @return <code>ActionErrors</code> object that encapsulates any
     * validation errors
     */
    public ActionErrors validate(ActionMapping mapping,
            HttpServletRequest request) {
        // Identify the request parameter containing the method name
        String parameter = mapping.getParameter();

        if( parameter != null ) {
            // Identify the method name to be dispatched to.
            String name = request.getParameter(parameter);
            MessageResources resources =
                (MessageResources) request.getAttribute(Globals.MESSAGES_KEY);
            // Identify the localized message for the cancel button
            String message = resources.getMessage("button.cancel");
            // if message resource matches the cancel button then no
            // need to validate
            if( name != null && name.equals(message) ) {
                if( log.isDebugEnabled() ) {
                    log.debug(mapping.getAttribute() + " '" + name +
                            "' method, so no need to validate");
                    return null;
                }
            }
        }
        // perform regular validation
        return super.validate(mapping, request);
    }

What do you think of this approach?

Regards,
--
Haroon Rafique [email protected] (reverse the domain to send email)

This looks good Haroon - thanks for the code sample. ~ MattRaible