php 57 lines · 8 steps

ETag caching and gzip in Laravel middleware

A Laravel middleware that adds conditional-request caching and gzip compression after the response is built.

Explained by highlit

Laravel Intermediate middleware http-caching etag compression conditional-requests

1<?php
2 
3namespace App\Http\Middleware;
4 
5use Closure;
6use Illuminate\Http\Request;
7use Symfony\Component\HttpFoundation\Response;
8 
9class CompressAndCacheResponse
10{
11    public function handle(Request $request, Closure $next): Response
12    {
13        $response = $next($request);
14 
15        if (!$this->shouldProcess($request, $response)) {
16            return $response;
17        }
18 
19        $body = $response->getContent();
20        $etag = '"' . md5($body) . '"';
21        $response->headers->set('ETag', $etag);
22        $response->headers->set('Cache-Control', 'private, must-revalidate, max-age=0');
23 
24        $ifNoneMatch = array_map('trim', explode(',', $request->headers->get('If-None-Match', '')));
25 
26        if (in_array($etag, $ifNoneMatch, true)) {
27            $response->setNotModified();
28            $response->headers->set('ETag', $etag);
29            return $response;
30        }
31 
32        if ($this->acceptsGzip($request) && strlen($body) > 1024) {
33            $compressed = gzencode($body, 6);
34            $response->setContent($compressed);
35            $response->headers->set('Content-Encoding', 'gzip');
36            $response->headers->set('Content-Length', (string) strlen($compressed));
37            $response->headers->set('Vary', 'Accept-Encoding');
38        }
39 
40        return $response;
41    }
42 
43    private function shouldProcess(Request $request, Response $response): bool
44    {
45        return $request->isMethod('GET')
46            && $response->isSuccessful()
47            && !$response->headers->has('Content-Encoding')
48            && str_contains((string) $response->headers->get('Content-Type'), 'text/')
49                || str_contains((string) $response->headers->get('Content-Type'), 'json');
50    }
51 
52    private function acceptsGzip(Request $request): bool
53    {
54        return str_contains($request->headers->get('Accept-Encoding', ''), 'gzip')
55            && function_exists('gzencode');
56    }
57}

01 / 01

STEP 01

Walkthrough

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Three takeaways

1Running logic after $next($request) lets middleware inspect and rewrite the fully-built response.
2An ETag derived from body content enables 304 responses that skip resending unchanged data.
3Operator precedence bugs like mixing && and || without parentheses can silently widen a guard clause.

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