php 47 lines · 9 steps

Streaming a large CSV export in Laravel

Export orders to CSV without loading the whole table into memory by streaming rows in chunks.

Explained by highlit

Laravel Intermediate streaming csv-export memory-efficiency pagination database

1<?php
2 
3namespace App\Http\Controllers;
4 
5use App\Models\Order;
6use Symfony\Component\HttpFoundation\StreamedResponse;
7 
8class OrderExportController extends Controller
9{
10    public function export(): StreamedResponse
11    {
12        $headers = [
13            'Content-Type' => 'text/csv; charset=UTF-8',
14            'Content-Disposition' => 'attachment; filename="orders.csv"',
15            'X-Accel-Buffering' => 'no',
16            'Cache-Control' => 'no-store, no-cache',
17        ];
18 
19        $columns = ['id', 'reference', 'customer_email', 'total_cents', 'status', 'placed_at'];
20 
21        return response()->stream(function () use ($columns) {
22            $out = fopen('php://output', 'w');
23            fputcsv($out, $columns);
24 
25            Order::query()
26                ->select($columns)
27                ->where('status', '!=', 'draft')
28                ->orderBy('id')
29                ->chunkById(2000, function ($orders) use ($out, $columns) {
30                    foreach ($orders as $order) {
31                        fputcsv($out, [
32                            $order->id,
33                            $order->reference,
34                            $order->customer_email,
35                            number_format($order->total_cents / 100, 2, '.', ''),
36                            $order->status,
37                            $order->placed_at?->toIso8601String(),
38                        ]);
39                    }
40 
41                    flush();
42                });
43 
44            fclose($out);
45        }, 200, $headers);
46    }
47}

01 / 01

STEP 01

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Three takeaways

1Streaming responses let you send data to the client as it's generated instead of buffering the entire payload in memory.
2chunkById paginates by primary key so a huge result set is processed in bounded batches rather than all at once.
3Disabling proxy and browser buffering plus calling flush ensures rows actually reach the client during generation.

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