Tree: DragDrop between trees get NPE in TabView DataModel

[lih13800]

Describe the bug

In the TabView with dynamic number of tabs (DataModel in the showcase http://www.primefaces.org:8080/showcase/ui/panel/tabView.xhtml?jfwid=e3889), drag-drop event between trigger a NullPointerException in TreeRenderer.java

SEVERE: java.lang.NullPointerException
	at org.primefaces.component.tree.TreeRenderer.decodeDragDrop(TreeRenderer.java:163)
	at org.primefaces.component.tree.TreeRenderer.decode(TreeRenderer.java:67)
	at javax.faces.component.UIComponentBase.decode(UIComponentBase.java:514)
	at org.primefaces.component.tree.Tree.processDecodes(Tree.java:270)

Tree otherTree = (Tree) tree.findComponent(separator + dragSource);
otherTree.setRowKey(otherTree.getValue(), rowKey);

https://github.com/primefaces/primefaces/blob/master/primefaces/src/main/java/org/primefaces/component/tree/TreeRenderer.java#L162-L163
In the code of TreeRenderer.java, "dragSource" is the id of the tree.

• The TabView with static tab number provides the correct component path, like this pattern :staticTabView:testTabForm:tree1.
• But TabView with dynamic tab number provides the component path with tab index like this dynamicTabView:0:testTabForm:tree1 (0 is tab index).

This might be the reason cause the findComponent() method return null value.

primefaces-test-master.zip

Reproducer

1. Go the lower TabView and select a tab
2. Drag the nodes from one tree to the other one
3. See error

SEVERE: java.lang.NullPointerException
	at org.primefaces.component.tree.TreeRenderer.decodeDragDrop(TreeRenderer.java:163)
	at org.primefaces.component.tree.TreeRenderer.decode(TreeRenderer.java:67)
	at javax.faces.component.UIComponentBase.decode(UIComponentBase.java:514)
	at org.primefaces.component.tree.Tree.processDecodes(Tree.java:270)

Expected behavior

There should be no NPE problem. The expected Result should the same as upper TabView.

PrimeFaces edition

None

PrimeFaces version

12.0.0

Theme

No response

JSF implementation

Mojarra

JSF version

2.2

Java version

JavaSE-1.8

Browser(s)

No response

[jepsar]

I don't see a tree and I don't understand what to drag from where to where.

[melloware]

@jepsar i was able to reproduce the NPE.

[melloware]

Bug is definitely right here:

String separator = Character.toString(UINamingContainer.getSeparatorChar(context));
Tree otherTree = (Tree) tree.findComponent(separator + dragSource);