Wicket AJAX + OnComponentTag

Question

HI guys, I wanted to add an AJAX Event to my Homepage, but it doesn't work! I figured out, that if I delete the onComponentTag function it works well. I have no clue why this happend, maybe you can help me! Thats my Code:

  final TextField<String> searchInput = new TextField<String>("searchInput", model) {

    @Override
    protected void onComponentTag(final ComponentTag tag) {
     super.onComponentTag(tag);
     tag.put("id", this.getId());
     if (params.getString("search") != null) {
      tag.put("value", params.getString("search"));
     }
    }
   };

   searchInput.add(new AjaxFormComponentUpdatingBehavior("onfocus") {
    @Override
    protected void onUpdate(final AjaxRequestTarget target) {
     System.out.print("never saw that message :(");
     searchInput.setDefaultModelObject("");
     target.addComponent(searchInput);
    }

   });

Thx a lot for helping me! CU

Answer 1

Firstly, you don't need to be overriding onComponentTag() at all. As seanizer states, if your really need to specify a markup ID yourself, use setMarkupId(id). You should understand why it is recommended that Wicket manages component IDs.

Secondly, the value attribute that you are adding is unnecessary - Wicket adds this automatically for this component. The value assigned is the value of the component's model object. See the source for TextField.onComponentTag().

Thirdly, again as seanizer states, components that are to be updated by ajax need to output their markup IDs - Wicket's ajax implementation uses the ID as the selector for the element. Additionally, all Wicket ajax behaviours that extend AbstractDefaultAjaxBehavior automatically set outputMarkupId(true) on the component they are bound to (see the source for AbstractDefaultAjaxBehavior.onBind()). This includes AjaxFormComponentUpdatingBehavior.

So:

String id = "searchInput";
final TextField<String> searchInput = new TextField<String>(id, model);
searchInput.setMarkupId(id);

searchInput.add(new AjaxFormComponentUpdatingBehavior("onfocus") {
  @Override
  protected void onUpdate(final AjaxRequestTarget target) {
    System.out.print("never saw that message :(");
    searchInput.setDefaultModelObject("");
    target.setOutputMarkupId(true);
    target.addComponent(searchInput);
  }
});

Finally, I'd question what you're actually trying to achieve with this behaviour. I don't see any reason to round-trip this event to the server. Surely some client-side JS is more appropriate?