CCrmInvoiceRestService::prepareOrder

static function prepareOrder($arOrder)
{
	$arResult = array();

	if (is_array($arOrder))
	{
		$fieldsInfo = self::getFieldsInfo();
		$userFields = CCrmInvoice::GetUserFields();
		foreach ($arOrder as $fieldName => $sortName)
		{
			$sortName = mb_strtoupper($sortName);
			if (isset($fieldsInfo[$fieldName])
				&& $fieldsInfo[$fieldName]['order'] === true
				&& ($sortName === 'ASC' || $sortName === 'DESC'))
			{
				$arResult[$fieldName] = $arOrder[$fieldName];
			}
			else
			{
				if(array_key_exists($fieldName, $userFields))
					$arResult[$fieldName] = ($sortName != 'ASC') ? 'DESC': 'ASC';
			}
		}
	}

	return $arResult;
}