ldc-crm/app/Http/Controllers/QuestionController.php

<?php

namespace App\Http\Controllers;

use App\Http\Controllers\Controller;
use App\Http\Requests\QuestionExport;
use App\Models\Brand;
use App\Models\Question;
use Carbon\Carbon;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;
use Kwaadpepper\CrudPolicies\Http\Requests\CrudIndexRequest;
use Kwaadpepper\CrudPolicies\Traits\CrudController;
use League\Csv\Writer;
use Symfony\Component\HttpFoundation\StreamedResponse;

class QuestionController extends Controller
{
    use CrudController {
        index as crudIndex;
    }

    /** @var Question */
    public static $modelClass = Question::class;

    public static $layout = 'layouts.app';

    public function index(CrudIndexRequest $request)
    {
        /** @var \Illuminate\View\View */
        $view = $this->crudIndex($request);
        if ($request->ajax()) {
            return $view;
        }
        return view('question.index', $view->getData());
    }

    public function indexQuery(Builder $query): Builder
    {
        if (request()->brand) {
            $query = $query->where('brand_id', '=', request()->brand);
        }
        return $query;
    }

    public function export()
    {
        $brands = Brand::all();
        return view('question.export', compact('brands'));
    }

    public function exportSubmit(QuestionExport $request)
    {
        $results   = [];
        $brand     = Brand::findOrFail($request->brand);
        $questions = $brand->questions->load('answers');

        foreach ($questions as $question) {
            $answersCounts = DB::query()
                ->selectRaw('count(*) as total, answer_id')
                ->from('customer_answer')
                ->whereIn('answer_id', $question->answers->pluck('id'))
                ->groupBy('answer_id')
                ->get()->keyBy('answer_id');

            $results[$question->id] = [
                'question' => $question->question,
                'answers' => []
            ];
            foreach ($question->answers as $answer) {
                $results[$question->id]['answers'][] =
                    [
                        "$answer->answer ",
                        $answersCounts[$answer->id]->total ?? 0
                    ];
            }
        }

        $pagination = 2000;

        $w = Writer::createFromString('');
        $w->setDelimiter(';');
        $w->setEnclosure('"');
        $w->setOutputBOM(Writer::BOM_UTF8);

        //We send the CSV using Symfony StreamedResponse
        $response = new StreamedResponse();
        $response->headers->set('Content-Encoding', 'none');
        $response->headers->set('Content-Type', 'text/csv; charset=UTF-8');
        $response->headers->set('Description', 'File Transfer');
        $response->headers->set(
            'Content-Disposition',
            sprintf(
                'attachment; filename="Export pour newsletter %s %s.csv"',
                Carbon::now()->format('d-m-Y_H-i'),
                Str::slug($brand->name)
            )
        );

        foreach ($results as $result) {
            $w->insertOne([
                'question' => $result['question'],
            ]);
            foreach ($result['answers'] as $answer) {
                $w->insertOne($answer);
            }
            $w->insertOne([]);
        }

        //we create a callable to output the CSV in chunk
        //with Symfony StreamResponse you can flush the body content if necessary
        //see Symfony documentation for more information
        $flush_threshold = 1000; //the flush value should depend on your CSV size.
        $response->setCallback(function () use ($w, $flush_threshold) {
            foreach ($w->chunk(1024) as $offset => $chunk) {
                echo $chunk;
                if ($offset % $flush_threshold === 0) {
                    flush();
                }
            }
        });
        return $response;
    }
}