Apache wicket: Componenet.replaceWith(component) from Linktree.onNodeSelected() - wicket

Question

I have a linktree for navigation over data which shall replace a component in another div.
For this in the tree I have the treestatelistener implementing
public void nodeSelected(Object node) {
log.debug("nodeSelected: " + node+ " class: " + node.getClass());
Component content = new Label("content");
content.replaceWith(new Label("content", "Hello World"));
}
}
}
All I get is the message:
"This method can only be called on a component that has already been
added to its parent."
The Label with Id "content" is added to the page on init, so it is there before. What do I do wrong?

Answer 1

You are creating a new parent Component every time your treenode listener is called, without adding the 'content' label.
What I would suggest is to try something like this -
public MyPage extends WebPage {
private Component parent = new WebMarkupContainer("parent");
public WebPage() {
parent.add(new Label("content", "hi");
}
...
public void nodeSelected(Object node) {
log.debug("nodeSelected: " + node+ " class: " + node.getClass());
parent.replaceWith(new Label("content", "Hello World"));
}
}
}

Answer 2

I always have issues with just calling Component.replaceWith(). Since I am doing this with AJAX, I always need to call a target.add().
My solution is for now to have a class MyTree extend LinkTree and in that class override the newNodeComponent().
Since in my application everything happens on the IndexPage.class and there I just replace components, I added a method handleSelection() to the IndexPage.Class(extends BasePage extends webpage). There I decide, based on the clicked nodeObject, how to replace a component in the IndexPage
Public Class MyTree extends Linktree{
protected Component newNodeComponent(String id, IModel<Object> model) {
#Override
protected void onNodeLinkClicked(Object node, BaseTree tree, AjaxRequestTarget target) {
super.onNodeLinkClicked(node, tree, target);
((IndexPage)getPage()).handleSelection(target, (TreeNode)node);
}
#Override
protected ResourceReference getResourceFolderOpen(Object node) {
return getResourceForNode(node);
}
#Override
protected ResourceReference getResourceFolderClosed(Object node) {
return getResourceForNode(node);
}
#Override
protected ResourceReference getResourceItemLeaf(Object node) {
return super.getResourceItemLeaf(node);
}
#Override
protected ResourceReference getImageResourceReference(BaseTree tree, Object node) {
return getResourceForNode(node);
}
}
}
I hope this is explained propperly, else: questions or comments wanted!