Trying to add a node in a TreeByNestingTableColumn

Question

Hello All,
I'm still having problems doing this!
I followed the tutorial step by step on how to Integrate a Tree structure in Web Dynpro table.
I'm using NWDS 7.0.18 on EP 7.0
The tutorial can be found [here|https://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/de59f7c2-0401-0010-f08d-8659cef543ce]
I changed mine around a little bit to use Levels.java instead of Catalog.java.
I got it working fine. Now the next step I want to do is add a toolbar button that will add a node in the tree structure. So I created the relevant button with an action onActionInsertNode and its signature its the same as the signature for Loading children nodes
public void onActionInsertNode(com.sap.tc.webdynpro.progmodel.api.IWDCustomEvent wdEvent,
com.sjm.wdp.wdp.IPrivateTreeAppCompView.ILEVELElement element )
    //@@begin onActionInsertNode(ServerEvent)
    addNewLevel(element.nodeCHILD_LEVEL(), element.getID()); // Null pointer exception here
    //@@end
I created a new method called addNewLevel to add a single element which is the new node. It looks like this
public void addNewLevel( com.sjm.wdp.wdp.IPrivateTreeAppCompView.ILEVELNode node,
java.lang.String parentId )
    //@@begin addNewLevel()
     IPrivateTreeAppCompView.ILEVELElement newLevelElement;
     if(parentId.equals(Levels.getParentId(node.LEAD_SELECTION)))
          newLevelElement = wdContext.nodeLEVEL().createLEVELElement();
          node.addElement(newLevelElement);
    //@@end
Now when I click the Insert Node button, I want to insert a new node underneath the selected node, ie I want to make it the child of the selected node. node.LEAD_SELECTION. If I look at my code it seems as if I'm following the same logic as the code provided by the tutorial, except the tutorial loops thru the multidimensional array in the Java file and I'm just trying to add a single child node.
I get a null pointer exception when the onActionInsertNode fires, Ive indicated above where.
Can someone kindly please explain what I am doing wrong?
Thanks in advance.
PS. I forgot to mention that when I created my action onActionInsertNode, I did NOT check the without validation checkbox. I don't actually know what this checkbox does, but in the tutorial is asks you to check this box when you create onActionLoadChildren.

Answer 1

Hi Armin,
So using what you have given me so far here is how the getTreeSelection().index() is returning
context                      getTreeSelection().index()
-Root                                       -1   
  - child1                                   0
    - gchild1_1                            0
      - leaf1_1                             0
      - leaf1_2                             1
    - gchild1_2                            1
    - gchild1_3                            2
  - child2                                   1
    - gchild2_1                            0
    - gchild2_2                            1
Here is my code to add a node into the desired position in the tree.
public void onActionInsertNode(com.sap.tc.webdynpro.progmodel.api.IWDCustomEvent wdEvent,
com.sjm.wdp.wdp.IPrivateTreeAppCompView.ILEVELElement element )
    //@@begin onActionInsertNode(ServerEvent)
    //addNewLevel(element.nodeCHILD_LEVEL(), element.getID());
    if(wdContext.nodeLEVEL().getLeadSelection() != IWDNode.NO_SELECTION)
         try
          IPrivateTreeAppCompView.ILEVELElement newChildElem =
                                                 wdContext.createLEVELElement();
          wdContext.nodeLEVEL().addElement
                               (wdContext.nodeLEVEL().getTreeSelection().index(), newChildElem);
     catch(Exception e)
    //@@end
However, despite specifying where to add the node, the node keeps getting created and added at the root level. Please help out.
Marshall.