How to get the AjaxRequestTarget inside Wicket'

问题:

I have an Ajax event that triggers the redraw of various Wicket panels. Some panels have additional calculations of their own inside their onBeforeRender() method. If there is an error, I want to display it to the user. But I can't add the FeedbackPanel to the AjaxRequestTarget because I don't have access to it anymore inside the panel that is being redrawn.

Is there a way to get the AjaxRequestTarget inside onBeforeRender() of a Wicket component? Is it even possible to add additional components to the Ajax target once the first ones are already in onBeforeRender() state?

Is there a better way to add the FeedbackPanel to the Ajax target if only the panels that need to be redrawn can decide if there is an error or not?

回答1:

Getting the AjaxTarget is done like this:

AjaxRequestTarget target = requestCycle.find(AjaxRequestTarget.class);

Unfortunately, like expected, I can't add components to the target once I'm in the rendering phase. But Wicket provides the interface ITargetRespondListener with the method onTargetRespond(AjaxRequestTarget target). Here I can add anything I want to the target.