getSelectFilters working with dates

[Kyle]

I am having trouble working out how to use getSelectFilters for dates.
I would like to setup the following filters
1) Start Date is <= Today
2) End Date is Null or >= Today

Unfortunately I can not find any examples in the source code. Is it possible to have 2 both rules for end date? Any help would be appreciated.

This is what i have, the value part does not work but I do get an empty filter shown for both fields.

        getSelectFilters: function () {
            return {

                'startDate': {
                    type: 'before',
                    value: 'today'
                },
                'endDate': {
                    type: 'after',
                    value: 'today'
                }
            };
        } 

[Kyle]

Part of the problem is solved, still looking for a way to handle Null or Future I am thinking I need to extend: \Espo\Core\SelectManagers\Base

        getSelectFilters: function () {
            return {
                'startDate': {
                    type: 'past'
                },
                'endDate': {
                    type: 'future'
                }
            };
        }