title: How can I load JSON into TreeStore?
body: <p>I would like to load a JSON file into a TreeStore to use in a TreePanel. I can load the store with values and have it display if I hard-code the tree, but when I try to load it from a JSON file it does not display anything in the tree. Here is my code:</p>
  
  <p>JSON file: exampleDoc.json</p>
  
  <pre><code>{
      "success": true, 
      "Root": [{
          "name": "Bookmark 1",
          "leaf": true,
          "element": "1"
      }, {
          "name":"Bookmark 2",
          "leaf": true,
          "element": "2"
      }, {
          "name":"Bookmark 3",
          "leaf": true,
          "element": "3"
      }]
  }
  </code></pre>
  
  <p>Here is my model</p>
  
  <pre><code>Ext.define('bkmark', {
      model: 'Ext.data.Model',
      fields: ['name', 'element']
  });
  </code></pre>
  
  <p>Here is my Tree Store</p>        
  
  <pre><code>var store = Ext.create('Ext.data.TreeStore', {
      model: 'bkmark',
      proxy: {
          type: 'ajax',
          url: 'exampleDoc.json',
          reader: {
              type: 'json'
          }
      }
  });
  </code></pre>
  
  <p>Here is my Tree Panel</p>
  
  <pre><code>var treePanel = Ext.create('Ext.tree.Panel', {
      title: 'Bookmarking',
      width: 225,
      height: 150,
      store: store,
      rootVisible: false,
      region: 'west',
      collapsible: true,
  });
  </code></pre>
  
  <p>Thanks in advance!</p>