title: Extjs 4 treepanel Reload and Expand
body: <p>I'm using Extjs4 treepanel with Json data.I want reload the treepanel and need expand tree menu to specified node.
  I'm using the following code. Please let me know how do this.</p>
  
  <pre><code>//Define tree store
  
  var store = Ext.create('Ext.data.TreeStore', {
      proxy: {
          type: 'ajax',
          url: 'my_tree.php',
      },
  
      noCache: false
  });
  
  // Treepanel
  var treePanel = Ext.create('Ext.tree.Panel', {
      id: 'mytree',
      renderTo: 'tree_div',
      height: 400,
      bodyBorder: false,
      border: false,
      singleExpand: true,
      rootVisible: false,
      store: store,
      useArrows: true
  });
  
  //Reload tree
      function reload_tree(){
         var tree_panel = Ext.getCmp('mytree');
          tree_panel.enable();
          tree_panel.getLoader().dataUrl = 'my_tree.php';
         tree_panel.getLoader().load(tree_panel.root);
         //Expand tree node
         tree_panel.getLoader().on('load', function(loader, node){ 
                tree_panel.getNodeById(nodeid).expand();
      //here node id is tree menu nodeid 
     });
     } 
  </code></pre>
  
  <p>Thanks in advance</p>