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

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!