Custom Sort (by date) in a DataGrid component

Question

So I've got a data grid component hooked up to a data provider like so:
var weekData:XML=// some xml loaded in earlier....
var weekGrid:DataGrid=new DataGrid();
var dataProvider:DataProvider=new DataProvider();
for each(var entry:XML in weekData){
     dp.addItem({event:entry.title,date:FormatDate.format(new Date(entry.@startDate),5),data:entry.@startDate});
The title column is just what you might think. The date colum is actually a format like May 2012 or Feb 2013. And the data "column" isn't actually shown in the dataGrid it is the "key" for sorting by date. It contains the getTime() value of the date like 1328515200000. So that will make date sorting just a case of Array.NUMERIC with the appropriate Array.DESCENDING when needed.
I've found that if I do this:
weekGrid.dataProvider.sortOn("data",Array.NUMERIC)
weekGrid.invalidate();
it works and the grid is sorted -- IF I have some other button to click to cause that code to run.
I want to tie it together with the click event on the grid header. Thusly:
weekGrid.addEventListener(DataGridEvent.HEADER_RELEASE,sortDataGrid);
And I've getting the event and all, but evidently that is fireing off the built-in sorting which happens after mine. And it doesn't do what I want.
Any idea how to stop that and allow my perferred sorting to take place?

Answer 1

if you don't want the user to sort your datagrid, use:
weekGrid.sortableColumns = false;
and execute your sort without clicking anything.  or use:
weekGrid.addEventListener(DataGridEvent.HEADER_RELEASE,sortDataGrid);
function sortDataGrid(e:DataGridEvent):void{
    setTimeout(sortF,100);
function sortF():void{
    weekGrid.dataProvider.sortOn("data",Array.NUMERIC)