After getting back the data from the server, I try to access the data in an AfterRender event
Code:
        afterRender: function(list){
          console.dir ( store.tree.root.childNodes );
          console.dir ( store.tree.root.childNodes[0] );
        }
The data I got back looks like:
{"text":".","children":[{"fileName":"locale","id":"locale","cls":"folder","queryStr":"gg=hh"},{"fileName":"data","id":".\/data","cls":"folder"}]}

I want to reach the gg=hh in the field "queryStr".
console.dir ( store.tree.root.childNodes );
gives me an Array with two objects, but
console.dir ( store.tree.root.childNodes[0] );
gives me an "undefined"?
Why do I get an undefined, although the array has two entries?

When I open the array in
console.dir ( store.tree.root.childNodes );
and open the first Element in the console further to 0.attributes.record.data
I see queryStr: "gg=hh"
How can I access the data in the treestore after is has been filled from the server?
Any help would be appreciated.
Torsten

Code:
Ext.regModel('File', {
  idProperty: 'id',
  fields: [{
    name: 'id',
    type: 'string'
  }, {
    name: 'fileName',
    type: 'string'
  }, {
    name: 'queryStr',
    type: 'string'
  }]
});

Ext.setup({
  icon: 'icon.png',
  tabletStartupScreen: 'tablet_startup.png',
  phoneStartupScreen: 'phone_startup.png',
  glossOnIcon: false,
  onReady: function(){
    var store = new Ext.data.TreeStore({
      model: 'File',
      proxy: {
        type: 'ajax',
        url: '/cgi-bin/nested.cgi?bb=cc',
        reader: {
          type: 'tree',
          root: 'children'
        }
      }
    });

    var nestedList = new Ext.NestedList({
      fullscreen: true,
      listeners: {
        afterRender: function(list){
          console.dir ( store.tree.root.childNodes );           // <- here I get the array
          console.dir ( store.tree.root.childNodes[0] );       // <- here I get undefined
        }
      },   
      title: 'src/',
      displayField: 'fileName',
      // add a / for folder nodes in title/back button
      getTitleTextTpl: function(){
        return '{' + this.displayField + '}<tpl if="leaf !== true">/</tpl>';
      },
      // add a / for folder nodes in the list
      getItemTextTpl: function(){
        return '{' + this.displayField + '}<tpl if="leaf !== true">/</tpl>';
      },
      store: store
    });
    
  }
});