EventRepository.php

См. документацию.

<?php
 
namespace Bitrix\Calendar\Event;
 
use Bitrix\Calendar\Internals\EventAttendeeTable;
use Bitrix\Calendar\Internals\EventTable;
use Bitrix\Main\Entity\ReferenceField;
use Bitrix\Main\ORM\Query\Join;
use Bitrix\Main\ORM\Query\Query;
 
final class EventRepository
{
    public static function getEventAttendeesCount(int $eventId): int
    {
        $eventsQuery = EventTable::query();
        $eventsQuery->registerRuntimeField(
            new ReferenceField(
                'ATTENDEES',
                EventAttendeeTable::getEntity(),
                Join::on('this.ID', 'ref.EVENT_ID')->where('ref.DELETED', 'N')
            )
        );
 
        $eventsQuery->addSelect(Query::expr()->count('ATTENDEES.ID'), 'ATTENDEES_COUNT');
        $eventsQuery->addGroup('ID');
        $eventsQuery->where('ID', $eventId);
 
        $result = $eventsQuery->fetch();
 
        return $result ? (int)$result['ATTENDEES_COUNT'] : 0;
    }
}