title: Extjs 4 nested xml into treepanel
body: <p>I have a java webservice I can't modify. It produce xml like :</p>
  
  <pre><code>&lt;query&gt;
      &lt;entity TYPE="Location"&gt;
          &lt;value TYPE="Id"/&gt;
          &lt;value TYPE="Class"/&gt;
          &lt;value TYPE="Name"/&gt;
      &lt;/entity&gt;
      &lt;entity TYPE="Activity"&gt;
          &lt;value TYPE="Id"/&gt;
          &lt;value TYPE="Date"/&gt;
          &lt;value TYPE="Duration"/&gt;
      &lt;/entity&gt;
  &lt;/query&gt;
  </code></pre>
  
  <p>I need to put the xml into the treestore, entities will be folder and values as leafs. I tried to describe 2 models with relations :</p>
  
  <pre class="lang-js prettyprint-override"><code>Ext.define( 'modelEntity' , {
      extend : 'Ext.data.Model' ,
          proxy: {
          type: 'ajax',
          url: 'query.xml', //just for tests
          reader: { type: 'xml' , root: 'query' , record: 'entity' } ,
      },
      fields: [
          {  name: 'leaf' ,  type: 'boolean', defaultValue: true} ,
          {  name: 'text' ,  type: 'string', mapping: '@TYPE'}
      ],
      hasMany: { model: "modelValue", name: "value",  }
  });
  
  Ext.define( 'modelValue' , {
      extend : 'Ext.data.Model' ,
      fields: [
          {  name: 'leaf' ,  type: 'boolean', defaultValue: true} ,
          {  name: 'text' ,  type: 'string', mapping: '@TYPE'}
      ],
      belongsTo: "modelEntity"
  });
  </code></pre>
  
  <p>with one treestore and a treepanel :</p>
  
  <pre class="lang-js prettyprint-override"><code>Ext.define('storeQuery' , {
      extend: 'Ext.data.TreeStore',   
      model: 'modelEntity',
      root: {
          expanded: true,
          leaf: false,
          children: []
      },
      autoLoad: false
  });
  
  Ext.create('Ext.tree.Panel', {
      store: Ext.create('storeQuery'),
      rootVisible: false
      ......
  });
  </code></pre>
  
  <p>Obviously it doesn't work, only entities are displayed, their children nodes aren't. Help me please ! =)</p>