title: xml base and relative query combination in qml
body: <p>I have the following xml :</p>
  
  <pre><code>&lt;response&gt;
  &lt;id&gt;...&lt;/id&gt;
  &lt;category_id&gt;...&lt;/category_id&gt;
  &lt;name&gt;...&lt;/name&gt;
  &lt;detail&gt;
      &lt;resource&gt;
          &lt;label&gt;...&lt;/label&gt;
          &lt;value&gt;...&lt;/value&gt;
      &lt;/resource&gt;
      &lt;resource&gt;
          &lt;label&gt;...&lt;/label&gt;
          &lt;value&gt;...&lt;/value&gt;
      &lt;/resource&gt;
  &lt;/detail&gt;
  &lt;price&gt;...&lt;/price&gt;
  &lt;currency&gt;...&lt;/currency&gt;
  &lt;/response&gt;
  </code></pre>
  
  <p>I need to get the id, name as well as label and value from one XmlListModel</p>
  
  <p>I have the following code:</p>
  
  <pre><code>XmlListModel {
      id: model
      query:"/response"
      source:"xml source"
  
      XmlRole { name: "name"; query: "name/string()"  }
      XmlRole { name: "id"; query:"id/number()"  }
      XmlRole { name: "label"; query: "detail/resource/label/string()" }
      XmlRole { name: "value"; query:"detail/resource/value/string()" }
  }
  </code></pre>
  
  <p>What is wrong with this code?
  Thanks.</p>