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.
来源：https://stackoverflow.com/questions/19246892/how-to-get-the-ajaxrequesttarget-inside-wickets-onbeforerender-method-of-a-co