title: PrimeNG TreeTable cannot get Row index
body: <p>Trying to use <code>rowIndex</code> inside <code>TreeTable</code>.
  With <code>DataTable</code> <code>rowIndex</code> works fine, but with <code>TreeTable</code> <code>rowIndex</code> is undefined.</p>
  
  <pre><code>&lt;p-treeTable [value]="files1"&gt;
    &lt;p-header&gt;Basic&lt;/p-header&gt;
    &lt;p-column header="ID"&gt;
      &lt;ng-template let-rowIndexValue="rowIndex" pTemplate="body"&gt;
        &lt;p class="rw-center-align"&gt;{{rowIndexValue}}&lt;/p&gt;
      &lt;/ng-template&gt;
    &lt;/p-column&gt;
    &lt;p-column field="name" header="Name"&gt;&lt;/p-column&gt;
    &lt;p-column field="size" header="Size"&gt;&lt;/p-column&gt;
    &lt;p-column field="type" header="Type"&gt;&lt;/p-column&gt;
    &lt;p-column header="Actions"&gt;
      &lt;ng-template let-rowIndexValue="rowIndex" pTemplate="body"&gt;
        &lt;button pButton label="Add child" (click)="addChild(rowIndex)"&gt;&lt;/button&gt;
      &lt;/ng-template&gt;
    &lt;/p-column&gt;
  &lt;/p-treeTable&gt;
  </code></pre>
  
  <p>Here in <code>addChild()</code> method I'm getting <code>rowIndexValue</code> as <code>undefined</code>, and <code>ID</code> column is empty.</p>