How to use functions like findNodeForKey, findTreeChildrenNodes etc. in Virtualized Tree

I made a Virtualized tree like from this sample:

I made the Virtualized tree as:

myWholeModel = $(go.TreeModel);
myDiagram.layout.model = myWholeModel;
myDiagram.model = $(go.TreeModel);

And populated it as:

myWholeModel.nodeDataArray = ndArray;

Now I want to use these functions but getting error when applying them on myWholeModel saying it cannot find the definition of these.

Without Virtualization, I could use these simply as :


But how can I use these functions as well as startTransaction, setDataProperty etc in Virtualized Tree?

The basic problem is that when you are virtualizing a diagram there might not be any Node for a particular node data object in the whole model.

So I suggest that you ask yourself if you really need access to that possibly non-existent Node, or if you could settle for dealing with the node data object, which should exist reliably and allow you to modify data properties in transactions. What do you want to do with such a Node that would normally not exist?