Datamapper: Something like where_in_related, but including all

[eluser]avramovic[/eluser]
OK, I'm looking like lunatic replying to myself constantly, but here's how I've done it, in case someone else needs similar functionality:

Code:

$results->where_in_related_amenity('id', $am_ids);
$results->group_by('id');
$results->having('COUNT(DISTINCT `'.$this->db->dbprefix.'amenities_properties`.`amenity_id`) =', count($am_ids), false);