I try with _value filter to save a blank field with a default value but no more luck...
add_filter('rwmb_row_id_value', 'rwmb_row_id',10,3);
function rwmb_row_id ( $new, $field, $old )
{
if ($old == '') $new = uniqid();
return $new ;
}
$old doesn't give me the old value of the field...
