title: Treegrid how use local json(memory proxy)
body: <p>My code:</p>
  
  <pre><code>Ext.onReady(function() {
      Ext.define('Unit', {
          extend: 'Ext.data.Model',
          fields: [
              {name: 'task',type: 'string'}
          ]
      });
  
      var store = Ext.create('Ext.data.TreeStore', {
          autoLoad: true,
          model: 'Unit',
          data:result,
          proxy: {
              type: 'memory',
              reader: {
                  type: 'json'
              }
          }
      });
       var tree = Ext.create('Ext.tree.Panel', {
          id:"treepanel",
          title: 'Core Team Projects',
          width: 500,
          height: 300,
          renderTo: Ext.getBody(),
          collapsible: true,
          useArrows: true,
          rootVisible: false,
          store: store,
          multiSelect: true,
          singleExpand: true,
          //the 'columns' property is now 'headers'
          columns: [{
              xtype: 'treecolumn', //this is so we know which column will show the tree
              text: 'Task',
              flex: 2,
              sortable: true,
              dataIndex: 'task'
          },{
              //we must use the templateheader component so we can use a custom tpl
              xtype: 'treecolumn',
              text: 'Duration',
              flex: 1,
              sortable: true,
              dataIndex: 'duration',
              align: 'center'
          }]
      });
  });
  </code></pre>
  
  <p>JSON is: <a href="http://dev.sencha.com/deploy/ext-4.0.0/examples/tree/treegrid.json" rel="nofollow">http://dev.sencha.com/deploy/ext-4.0.0/examples/tree/treegrid.json</a></p>
  
  <p>The tree don't display my result, how to do it? I am a new ExtJs4.</p>
  
  <p>Sorry I don't want to use AJAX for get result.</p>