Question

if I have an input wrapped in a div (together with other stuff),
how can I pass to that input whatever beavior is added to the wrapper?

Example:
Component HTML goes like <div> <img> <input> ...
Then I’d like to add it like add( new MyComponent("foo", model).add( new AjaxEventBehavior("onupdate"){ ... } (but that doesn’t work since only FormComponent can receive (AjaxEventBehavior`s).

I assume I could move this behavior object from wrapper to input, but don’t know where – is there some “after construction” listener?
Or should I do it completely different, like passing the behavior as a parameter?
The reason to keep it like above is to make it transparent for the user of the component.

Answer 1

You could override the MarkupContainer#add(Behavior... behaviors) method of the wrapping component. This would of course mean that the wrapping component could never receive any behaviors:

public class MyWrappingComponent extends Panel {
    private TextField<?> field;

    // Constructors and stuff..

    @Override
    public Component add(Behavior... behaviors) {
        field.add(behaviors);
        return this;
    }
}

One option is to separate the wrapping component to be a Border, which can be used to surround components with content. This would, however, reduce the “transparency” of the wrapping element. (See the example on the Javadoc page).

public class MyWrappingBorder extends Border {
    public MyWrappingBorder(String id) {
        // add the <img />
        // add the <div />
    }
    ...
 }

 // The markup
 <wicket:border>
     <div>
        <img />
        <wicket:body /> <!-- Will be replaced with the added content -->
     </div>
 </wicket:border>

Then use it like this:

 add(new MyWrappingBorder("border")
     .add(new TextField<String>("input").add(/* the behaviors */)));

With this kind of markup

 <div wicket:id="border">
     <input type="text" wicket:id="input" />
 </div>

The Border approach would enable you to reuse the border component without the `TextField? component. E.g., if you want to add a drop-down:

 add(new MyWrappingBorder("border")
     .add(new DropDownChoice<String>("input", listOfChoices)));