CgridView dropdown filter for null/empty values

Hi All,

I’ve created a dropdown cgridview which works great:




array(

    'name'=>'

    'value'=>'$data->tags->

    'filter' => CHtml::listData(Tags::model()->findAll(), 'id', 'tag'),

),



Is there a way to add an option to my dropdown to search specifically for items that are empty/null/blank?

I know with CHtml::dropDownList i can add an array element ‘’=>‘untagged’ but that will show all tags.

Any thoughts?

Thanks

Oliver