bitrix_seo_count_elements_in_section.php

<? require_once($_SERVER['DOCUMENT_ROOT'].'/bitrix/modules/iblock/lib/template/functions/fabric.php');

use Bitrix\Main;

$eventManager = Main\EventManager::getInstance();
$eventManager->addEventHandler("iblock", "OnTemplateGetFunctionClass", "myOnTemplateGetFunctionClass");

function myOnTemplateGetFunctionClass(Bitrix\Main\Event $event) {
   $arParam = $event->getParameters();
   $functionClass = $arParam[0];
   if (is_string($functionClass) && class_exists($functionClass) && $functionClass=='count_section'){
      $result = new Bitrix\Main\EventResult(1,$functionClass);
      return $result;
   }
}

class count_section extends Bitrix\Iblock\Template\Functions\FunctionBase
{
   public function onPrepareParameters(\Bitrix\Iblock\Template\Entity\Base $entity, $parameters)
   {
      $arguments = array();
      /** @var \Bitrix\Iblock\Template\NodeBase $parameter */
      foreach ($parameters as $parameter)
      {
         $arguments[] = $parameter->process($entity);
      }
      return $arguments;
   }

   public function calculate(array $parameters)
   {
    $arFilter = Array(
    "IBLOCK_ID"=>IntVal($parameters[0]),
    "SECTION_CODE" => $parameters[1],
    "ACTIVE"=>"Y",
    "INCLUDE_SUBSECTIONS" => 'Y'
    );
    $res = CIBlockElement::GetList(Array("SORT"=>"ASC"), $arFilter, Array("ID"));
    if($count = $res->SelectedRowsCount()){
    $activeElements = $count;
    }
    return $activeElements;
   }
}
//пример вызова в сео модуле {=count_section 4 this.Code} где 4 id инфоблока, а this.Code символьный код раздела