filtering for checkbox with null values

[kshipra]

I have nullable boolean values in database and when shown in grid, checkbox is shown as unknown. How can I provide filtering ability for checkboxes with unknown text ? . I can filter only for true/ false or both. But would like to filter for unknowns.

Thanks

[paramvir]

You would need a drop down filter in the header and custom filtering condition as in this example

https://paramquery.com/pro/demos/filter_custom