Edit file File name : WeeklyInvoiceCalculator.php Content :<?php /* * This file is part of the Kimai time-tracking app. * * For the full copyright and license information, please view the LICENSE * file that was distributed with this source code. */ namespace App\Invoice\Calculator; use App\Invoice\CalculatorInterface; use App\Invoice\InvoiceItemInterface; /** * A calculator that sums up the invoice item records per week. */ class WeeklyInvoiceCalculator extends AbstractSumInvoiceCalculator implements CalculatorInterface { protected function calculateSumIdentifier(InvoiceItemInterface $invoiceItem): string { return $invoiceItem->getBegin()->format('W'); } /** * @return string */ public function getId(): string { return 'weekly'; } } Save