HTTP Caching

Slim 3 uses the optional standalone slimphp/Slim-HttpCache PHP componentfor HTTP caching. You can use this component to create and return responses thatcontain Cache, Expires, ETag, and Last-Modified headers that controlwhen and how long application output is retained by client-side caches. You may have to set your php.ini setting “session.cache_limiter” to an empty string in order to get this working without interferences.

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 applicationmiddleware. You should add both to your application like this:

// Register service provider with the container
$container = new \Slim\Container;
$container['cache'] = function () {
    return new \Slim\HttpCache\CacheProvider();
};
// Add middleware to the application
$app = new \Slim\App($container);
$app->add(new \Slim\HttpCache\Cache('public', 86400));
// Create your application routes...
// Run application
$app->run();

ETag

Use the service provider’s withEtag() method to create a Response objectwith the desired ETag 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 objectwith 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 objectwith 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;
});