Question

In Apache Wicket web framework every component returns false from getOuputMarkupId() by default.

I am curious about the reason. The design decision behind.

I am using ajax components and I need to refresh some others components on a page. To do that I got to setOutputMarkupId(true) on every component which is involved in ajax page refreshing. Because I heavily use ajax I got to do it very often.
And it’s not very convenient. Besides “The Best Code is No Code At All“.

I can handle it this way:

class MyApp extends Application {

   @Override
   public init() {

       Application.addComponentInstantiationListener(
            new  IComponentInstantiationListener() {

                   public void onInstantiation(Component component) {
                      component.setOutputMarkupId(true);
                      component.setOutputMarkupPlaceholderTag(true);
                   }

            }
       );

But is there any trade-off?
Only trade-offs comes to my mind are:

• rendered page (html) is larger
• there is some rendering overhead (ie. when id attributes are write down to html)

But those have only small footprint imho.

Answer 1

It can’t pickup id’s from the .html (yet, it can in 1.5).
So this would override those id’s, that you may be using for css/js etc