I have a Task model with a DueDate SS_Datetime field. To see the 'soonest due' tasks first, I sort my tasks by DueDate ASC.. This works as expected, apart from the fact that tasks without due dates are shown before tasks with due dates.

I was wondering if there was a custom sort; or a field modifier like sort('DueDate:exists') etc?

Alternatively, I can create a HasDueDate Boolen field that's set to !empty($this->DueDate) onBeforeWrite, but maybe there is a better way?

Maybay this is a little bit nicer:

In ModelAdmin:

public function getList(){
		$list = parent::getList();
		$list->exclude('DueDate', ' '); //or try: $list->exclude('DueDate', null); 
                return $list;
}

With these function you exclude all empty DueDates from listview.

$list->where('DueDate IS NOT NULL');

Your suggestions are much appreciated guys, but I'm looking for a SORT not a filter :) (sort null before asc).

So I will probably do 2 data queries, one for null due dates and one for tasks that have them.