I use WebHierarchicalDataGrid with two levels.

I need to implement following scenario:

1. The grid's initially populated only with first-level rows. (the rows have no child rows)

2. User does some action (for ex. clicks on a button) and a child row is added to the selected parent row.

I've done it in following way:

       var selectedRow = getSelectedRow();
        var childGrid = selectedRow.get_rowIslands()[0];
        var row = new Array("");
        childGrid.get_rows().add(row);

This approach works fine if parent row already has at least one child row, but if there is no child rows I get null reference exception: selectedRow.get_rowIslands() returns  empty array.

Please help!