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

Walkthrough

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

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