chill-bundles/src/Bundle/ChillCalendarBundle/Export/Aggregator/MonthYearAggregator.php

<?php

namespace Chill\CalendarBundle\Export\Aggregator;

use Chill\CalendarBundle\Export\Declarations;
use Chill\MainBundle\Export\AggregatorInterface;
use Closure;
use Doctrine\ORM\QueryBuilder;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Security\Core\Role\Role;

class MonthYearAggregator implements AggregatorInterface
{

    public function getQueryKeys($data): array
    {
        return ['month_year_aggregator'];
    }

    public function getLabels($key, array $values, $data): Closure
    {
        return function($value): string {
            if ($value === '_header') {
                return 'by month and year';
            }

            $month = substr($value,0, 2);
            $year = substr($value, 3, 4);

            return strftime('%B %G', mktime(0, 0, 0, $month, '1', $year));
        };
    }

    public function buildForm(FormBuilderInterface $builder)
    {
        // No form needed
    }

    public function getTitle(): string
    {
        return 'Group by month and year';
    }

    public function addRole(): ?Role
    {
        return null;
    }

    public function alterQuery(QueryBuilder $qb, $data)
    {
        $qb->addSelect("to_char(cal.startDate, 'MM-YYYY') AS month_year_aggregator");
        // $qb->addSelect("extract(month from age(cal.startDate, cal.endDate)) AS month_aggregator");
        $groupBy = $qb->getDQLPart('groupBy');

        if (!empty($groupBy)) {
            $qb->addGroupBy('month_year_aggregator');
        } else {
            $qb->groupBy('month_year_aggregator');
        }
    }

    public function applyOn(): string
    {
        return Declarations::CALENDAR_TYPE;
    }
}