HomeController.php

<?php

namespace App\Controller;

use App\Entity\User;
use Doctrine\ORM\EntityManagerInterface;
use PhpOffice\PhpSpreadsheet\Spreadsheet;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;
use Symfony\Component\Routing\Annotation\Route;

class HomeController extends AbstractController
{
    /**
     * @var EntityManagerInterface
     */
    private $entityManager;

    public function __construct( EntityManagerInterface $entityManager)
    {

        $this->entityManager = $entityManager;
    }

    /**
     * @Route("/", name="home")
     */
    public function home()
    {
        return $this->render('home/index.html.twig', [
            'controller_name' => 'HomeController',
        ]);
    }

    private function getData(): array
    {
        /**
         * @var $user User[]
         */
        $list = [];
        $users = $this->entityManager->getRepository(User::class)->findAll();

        foreach ($users as $user) {
            $list[] = [
                $user->getFullName(),
                $user->getEmail(),
                $user->getBirthday()
            ];
        }
        return $list;
    }

    /**
     * @Route("/export",  name="export")
     */
    public function export()
    {
        $spreadsheet = new Spreadsheet();

        $sheet = $spreadsheet->getActiveSheet();

        $sheet->setTitle('User List');

        $sheet->getCell('A1')->setValue('Full Name');
        $sheet->getCell('B1')->setValue('Mail');
        $sheet->getCell('C1')->setValue('Birthday');

        // Increase row cursor after header write
            $sheet->fromArray($this->getData(),null, 'A2', true);
        

        $writer = new Xlsx($spreadsheet);

        $writer->save('helloworld.xlsx');

        return $this->redirectToRoute('home');
    }
}