File::countAttachedObjects

public function countAttachedObjects()
{
	$countQuery = new Query(AttachedObjectTable::getEntity());
	$countQuery
		->addSelect(new ExpressionField('CNT', 'COUNT(1)'))
		->setFilter(array(
			'=OBJECT_ID' => $this->id,
			'=VERSION_ID' => null,
		))
	;

	$totalData = $countQuery->setLimit(null)->setOffset(null)->exec()->fetch();

	return $totalData['CNT'];
}