How to change first sort direction on WPF DataGridColumn

Question

Right now (default) when you click a header on a user sortable DataGridColumn it sorts it ascending on first click and descending on second click.

How can I make it sort descending on first click and ascending on second click?

Answer 1

I figured out a way to do it, not sure if it is the best way. But basically when the sorting event triggers and the current SortDirection is null I set it to Ascending so that the default sorter will reverse the SortDirection to descending, and this only happens on the first sort because that is the only time the SortDirection is null.

myGrid.Sorting += (s, e) => e.Column.SortDirection = e.Column.SortDirection ?? ListSortDirection.Ascending;

Answer 2

Here's an expanded version of the accepted answer (I'm not a fan of that compact notation):

private void _myGrid_Sorting(object sender, DataGridSortingEventArgs e)
{
    if (e.Column.SortDirection == null)
        e.Column.SortDirection = ListSortDirection.Ascending;
}