Example streaming large CSV files with Laravel and thousands of queries

download_csv.php

<?php

namespace Src\Csv;

use Illuminate\Http\Response;
use Symfony\Component\HttpFoundation\StreamedResponse;

/**
 * Class DownloadLargeCsv
 *
 * @package Src\Csv
 *
 * This class set streaming large csv chunking queries
 *
 */
class DownloadLargeCsv
{
    const SIZE_CHUNK = 200;
    
    const DOWNNLOAD_NAME = 'filename_example.csv';
    
    private $fileHandle;
    
    
    public function execute()
    {
        return new StreamedResponse(function () {
            
            $this->openFile();
            
            $this->addBomUtf8();
            
            $this->addContentHeaderInFile();
            
            $this->processUsers();
            
            $this->closeFile();
            
        }, Response::HTTP_OK, $this->headers());
    }
    
    private function openFile()
    {
        $this->fileHandle = fopen('php://output', 'w');
    }
    
    private function addBomUTf8 (){
        fwrite($this->fileHandle, $bom = (chr(0xEF).chr(0xBB).chr(0xBF)));
    }
    
    private function addContentHeaderInFile()
    {
        $this->putRowInCsv([
            'Example header 1',
            'Example header 2',
            'Example header 3'
        ]);
    }
    
    private function processUsers()
    {
        User::with(['posts'])->chunk(self::SIZE_CHUNK, function ($users) {
            
            foreach ($users as $user) {
                $this->addUserLine($user);
            }
            
        });
    }
    
    private function addUserLine(User $user)
    {
        $this->putRowInCsv([    $user->exampleContent1(),
                            $user->exampleContent2(),
                            $user->exampleContent3()
                       ]);
    }
    
    private function putRowInCsv (array $data){
        fputcsv($this->fileHandle, $data, ';');
    }
    
    private function closeFile()
    {
        fclose($this->fileHandle);
    }
    
    private function headers()
    {
        return [
            'Content-Type' => 'text/csv',
            'Content-Disposition' => 'attachment; filename="'.self::DOWNNLOAD_NAME.'"',
        ];
    }
}