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20040227 Friday February 27, 2004

Generating indexed-property ready ActionForms with XDoclet One of the issues with using XDoclet to generate your Struts ActionForms (from POJOs) is that out-of-the-box, your Forms will not support indexed properties. This means that if you have a List on an object (this list will likely contain other objects/forms), you have to extend the generated form to add the necessary setters for indexed properties. For example, if you have an addresses List on a PersonForm, you would need the following in order to edit those addresses in Struts.

    setAddresses(int index, Object address) {
        this.addresses.set(index, address);
    }

The worst part is that you need to populate the addresses list with a bunch of empty AddressForm objects before Struts' auto-population will succeed. If you were coding the PersonForm by hand, you could code a reset() method such as the following:

    public void reset(ActionMapping mapping, HttpServletRequest request) {
        this.addresses = ListUtils.lazyList(new ArrayList(), new ObjectFactory());
    }

    /**
     * <code>StringFactory</code>
     *
     * @see org.apache.commons.ListUtils
     */
    class ObjectFactory implements Factory {

        /**
         * Create a new instance of the specified object
         */
        public Object create() {
            return new AddressForm();
        }
    }

Now for the best part - I figured out how to generate this code with XDoclet, so any lists on your Forms will be indexed-property ready. By using <nested:iterate> in your JSP, you can easily CRUD you indexed properties. Pretty slick IMHO. The template is a bit much to put on this site, and it's long lines won't fit in a <pre> - so you can temporarily view the template here. I'll add a link to it in AppFuse's CVS once it shows up there. One thing you'll notice in this template is a little Velocity-lovin': 

<XDtVelocity:generator>
  #set( $method = $currentMethod.name)
  ## trim off the 'get'
  #set( $objectName = $method.substring(3, $method.lastIndexOf('s')))
</XDtVelocity:generator>

Thanks to Erik on Merrick's blog for the quick Velocity/XDoclet howto. It was especially helpful since the XDoclet site has no documentation on this feature.

For all you my framework is better junkies - a clear explanation of how your framework handles indexed properties would be appreciated.

Posted in Java at Feb 27 2004, 05:18:10 PM MST 2 Comments

Comments:

I'm using Netscape 7.1 and i pasted below how your text appears on the browser. All your formatting seems to be ignored. -- paste start here ... One of the issues with using [XDoclet|http://xdoclet.sf.net] to generate your Struts ActionForms (from POJOs) is that out-of-the-box, your Forms will not support indexed properties. This means that if you have a List on an object (this list will likely contain other objects/forms), you have to extend the generated form to add the necessary setters for indexed properties. For example, if you have an addresses List on a PersonForm, you would need the following in order to edit those addresses in Struts. [{Java2HtmlPlugin setAddresses(int index, Object address) { this.addresses.set(index, address); } }] José.

Posted by Jose Nyimi on June 26, 2004 at 05:35 AM MDT #

Should be fixed now - thanks for the heads up Jose.

Posted by Matt Raible on June 26, 2004 at 06:47 AM MDT #

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Matt Raible is a Web Architecture Consultant specializing in open source frameworks.
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