BasketReservationHistoryService::getQuantityByReservation

public function getQuantityByReservation(int $reservationId): float
{
	$total = 0.0;

	$rows = BasketReservationHistoryTable::getList([
		'select' => [
			'QUANTITY',
		],
		'filter' => [
			'=RESERVATION_ID' => $reservationId,
		],
	]);
	foreach ($rows as $row)
	{
		$total += (float)$row['QUANTITY'];
	}

	return $total;
}