title: DataGridColumn with ItemRenderer, how to set dataProvider properly?
body: <p>I'm building a DataGrid to display data similar to the following XML:</p>
  
  <pre><code>&lt;foo&gt;
      &lt;entities&gt;
          &lt;entity&gt;
              &lt;name&gt;Jim&lt;/name&gt;
              &lt;trend&gt;
                  &lt;quantity&gt;10&lt;/quantity&gt;
                  &lt;quantity&gt;20&lt;/quantity&gt;
                  &lt;quantity&gt;30&lt;/quantity&gt;
              &lt;/trend&gt;
         &lt;/entity&gt;
         ...
      &lt;/entities&gt;
  &lt;/foo&gt;
  </code></pre>
  
  <p>The idea is to have the grid display the name in one column and a small graphic (sparkline) in the second column based on the quantities.  I have a sparkline component that needs an ArrayList as a dataProvider.  My grid is set up thusly:</p>
  
  <pre><code>&lt;!-- XML from dataservice transformed into XMLListCollection --&gt;
  &lt;mx:XMLListCollection id="xmlcol" source="{xmlData.entities.entity}"/&gt;
  &lt;mx:DataGrid id="thegrid" dataProvider="{xmlcol}"&gt;
      &lt;mx:columns&gt;
          &lt;mx:DataGridColumn id="name" dataField="name" headerText="Name" /&gt;
          &lt;mx:DataGridColumn id="spark" dataField="trend.quantity" header="Trend"&gt;
              &lt;mx:itemRenderer&gt;
                  &lt;mx:Component&gt;
                       &lt;mycomponents:Sparkline dataProvider="?????????" /&gt;
                  &lt;/mx:Component&gt;
              &lt;/mx:itemRenderer&gt;
          &lt;/mx:DataGridColumn&gt;
     &lt;/mx:columns&gt;
  &lt;/mx:DataGrid&gt;
  </code></pre>
  
  <p>What is the best way (or anyway!) to set the dataProvider for the Sparkline component to the array of quantities?  Do I need the dataField in the enclosing DataGridColumn?  Is my approach all wrong?</p>
  
  <p>As always, thanks in advance for any help you can provide.</p>
  
  <p>TB</p>