Re: 'firstChild' is null or not an object - Error by deleting the last node of the CellTree

I have just come across the same issue in GWT 2.5.1 on IE8/9/10. I've used CellTrees a lot and never seen this issue before.

I have avoided the issue by disabling the keyboard selection

tree.setKeyboardSelectionPolicy(KeyboardSelectionPolicy.DISABLED);

P.

On Thursday, 7 July 2011 11:36:15 UTC+1, rmartinsfidalgo wrote:

Hi

I have a little issue about the CellTree specially by deleting the
last node.
I created a normal CellTree with a root node and data nodes like this:

ROOT
     >DATA A
     >DATA B
     >DATA C

The Root contain the dataProvider (which is ListDataProvider) where I
add data nodes or deleted.
For adding the code is:
  dataProvider.getList().add(node);
  dataProvider.refresh();
For deleting the code is:
   if (childNode != null && dataProvider.getList().contains(node)) {
      dataProvider.getList().remove(node);
      dataProvider.refresh();
   }


This works fine in Chrome and in Firefox 3.5.

But for IE 8.0. when I deleting the last node (in this case the DATA
C) there is an JavaScriptException see below.

Is there a workaround?

com.google.gwt.core.client.JavaScriptException: (TypeError):
'firstChild' is null or not an object
 number: -2146823281
 description: 'firstChild' is null or not an object
        
com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:
237)
        
com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:
129)
        com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:
561)
        
com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:
269)
        
com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:
91)
        com.google.gwt.dom.client.DOMImpl.getFirstChildElement(DOMImpl.java)
        com.google.gwt.dom.client.Element$.getFirstChildElement$(Element.java:
241)
        
com.google.gwt.user.cellview.client.CellTreeNodeView.getCellParent(CellTreeNodeView.java:
660)
        
com.google.gwt.user.cellview.client.CellTreeNodeView.getCellParent(CellTreeNodeView.java:
1039)
        
com.google.gwt.user.cellview.client.CellTreeNodeView.setKeyboardSelected(CellTreeNodeView.java:
1234)
        
com.google.gwt.user.cellview.client.CellTree.keyboardSelect(CellTree.java:
884)
        com.google.gwt.user.cellview.client.CellTreeNodeView$NodeCellList
$View.loadChildState(CellTreeNodeView.java:340)
        com.google.gwt.user.cellview.client.CellTreeNodeView$NodeCellList
$View.replaceAllChildren(CellTreeNodeView.java:211)
        
com.google.gwt.user.cellview.client.HasDataPresenter.resolvePendingState(HasDataPresenter.java:
1348)
        com.google.gwt.user.cellview.client.HasDataPresenter.access
$3(HasDataPresenter.java:1112)
        com.google.gwt.user.cellview.client.HasDataPresenter
$2.execute(HasDataPresenter.java:1037)
        com.google.gwt.core.client.impl.SchedulerImpl$Task$.executeScheduled$
(SchedulerImpl.java:50)
        
com.google.gwt.core.client.impl.SchedulerImpl.runScheduledTasks(SchedulerImpl.java:
229)
        
com.google.gwt.core.client.impl.SchedulerImpl.flushFinallyCommands(SchedulerImpl.java:
328)
        com.google.gwt.core.client.impl.Impl.exit(Impl.java:238)
        com.google.gwt.core.client.impl.Impl.entry0(Impl.java:229)
        sun.reflect.GeneratedMethodAccessor40.invoke(Unknown Source)
        
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
25)
        java.lang.reflect.Method.invoke(Method.java:597)
        com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
        com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:
71)
        
com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:
157)
        
com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:
281)
        
com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:
531)
        
com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:
352)
        java.lang.Thread.run(Thread.java:662)

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