HTTP Caching

Slim 3 uses the optional standalone slimphp/Slim-HttpCache PHP component for HTTP caching. You can use this component to create and return responses that contain Cache,Expires, ETag, and Last-Modified headers that control when and how long application output is retained by client-side caches.

Installation

Execute this bash command from your project’s root directory:

composer require slim/http-cache

Usage

The slimphp/Slim-HttpCache component contains a service provider and an application middleware. You should add both to your application like this:

// Register service provider with the container
$container = new SlimContainer;
$container["cache"] = function () {
    new SlimHttpCacheCacheProvider();
};

// Add middleware to the application
$app = new SlimApp($container);
$app->add(new SlimHttpCacheCache("public", 86400));

// Create your application routes...

// Run application
$app->run();

ETag

Use the service provider’s withEtag() method to create a Response object with the desiredETag header. This method accepts a PSR7 response object, and it returns a cloned PSR7 response with the new HTTP header.

$app->get("/foo", function ($req, $res, $args) {
    $resWithEtag = $this->cache->withEtag($res, "abc");

    return $resWithEtag;
});

Expires

Use the service provider’s withExpires() method to create a Response object with the desired Expires header. This method accepts a PSR7 response object, and it returns a cloned PSR7 response with the new HTTP header.

$app->get("/bar",function ($req, $res, $args) {
    $resWithExpires = $this->cache->withExpires($res, time() + 3600);

    return $resWithExpires;
});

Last-Modified

Use the service provider’s withLastModified() method to create a Response object with the desired Last-Modified header. This method accepts a PSR7 response object, and it returns a cloned PSR7 response with the new HTTP header.

//Example route with LastModified
$app->get("/foobar",function ($req, $res, $args) {
    $resWithLastMod = $this->cache->withLastModified($res, time() - 3600);

    return $resWithLastMod;
});