$ composer require php-http/cache-plugin
CachePlugin allows you to cache responses from the server. It can use
any PSR-6 compatible caching engine. By default, the plugin respects the cache
control headers from the server as specified in RFC 7234. It needs a
stream and a PSR-6 implementation:
use Http\Discovery\HttpClientDiscovery; use Http\Client\Common\PluginClient; use Http\Client\Common\Plugin\CachePlugin; /** @var \Psr\Cache\CacheItemPoolInterface $pool */ $pool = ... /** @var \Http\Message\StreamFactory $streamFactory */ $streamFactory = ... $options = ; $cachePlugin = new CachePlugin($pool, $streamFactory, $options); $pluginClient = new PluginClient( HttpClientDiscovery::find(), [$cachePlugin] );
CachePlugin has also 2 factory methods to easily set up the plugin by caching type. See the example below.
// This will allow caching responses with the 'private' and/or 'no-store' cache directives $cachePlugin = CachePlugin::clientCache($pool, $streamFactory, $options); // Returns a cache plugin with the current default behavior $cachePlugin = CachePlugin::serverCache($pool, $streamFactory, $options);
The two factory methods have been added in version 1.3.0.
The third parameter to the
CachePlugin constructor takes an array of options. The available options are:
||The default max age of a Response|
||Whether we should care about cache headers or not * This option is deprecated. Use respect_response_cache_directives|
||30 days||The minimum time we should store a cache item|
||Which request methods to cache|
||A list of cache directives to respect when caching responses|
||A class implementing
||A array of classes implementing
A HTTP response may have expired but it is still in cache. If so, headers like
If-None-Match are added to the HTTP request to allow the server answer with 304 status code. When
a 304 response is received we update the CacheItem and save it again for at least
Using these options together you can control how your responses should be cached. By default, responses with no
cache control headers are not cached. If you want a default cache lifetime if the server specifies no
$options = [ 'default_ttl' => 42, // cache lifetime time in seconds ];
You can tell the plugin to completely ignore the cache control headers from the server and force caching the response for the default time to live. The options below will cache all responses for one hour:
$options = [ 'default_ttl' => 3600, // cache for one hour 'respect_response_cache_directives' => , ];
Generating a cache key¶
You may define a method how the PSR-6 cache key should be generated. The default generator is
is using the request method, URI and body of the request. The cache plugin does also include a
which allow you to specify what HTTP header you want include in the cache key.
Controlling cache listeners¶
One or more classes implementing
CacheListener can be added through
cache_listeners. These classes recieve a
notification on whether a request was a cache hit or miss, and can optionally mutate the response based on those signals.
As an example, adding the provided
AddHeaderCacheListener will mutate the response, adding an
X-Cache header with
MISS, which can be useful in debugging.
Semantics of null values¶
Setting null to the options
default_ttl means “Store this as long as you can (forever)”.
This could be a great thing when you requesting a pay-per-request API (e.g. GoogleTranslate).
Store a response as long the cache implementation allows:
$options = [ 'default_ttl' => null, 'respect_response_cache_directives' => , 'cache_lifetime' => null, ];
Ask the server if the response is valid at most ever hour. Store the cache item forever:
$options = [ 'default_ttl' => 3600, 'respect_response_cache_directives' => , 'cache_lifetime' => null, ];
Ask the server if the response is valid at most ever hour. If the response has not been used within one year it will be removed from the cache:
$options = [ 'default_ttl' => 3600, 'respect_response_cache_directives' => , 'cache_lifetime' => 86400*365, // one year ];
Caching of different request methods¶
Most of the time you should not change the
methods option. However if you are working for example with HTTPlug
based SOAP client you might want to additionally enable caching of
$options = [ 'methods' => ['GET', 'HEAD', 'POST'], ];
methods setting overrides the defaults. If you want to keep caching
HEAD requests, you need
to include them. You can specify any uppercase request method which conforms to RFC 7230.
If your system has both normal and SOAP clients you need to use two different
PluginClient instances. SOAP
client should use
PluginClient with POST caching enabled and normal client with POST caching disabled.
Cache Control Handling¶
By default this plugin does not cache responses with
private instructions. Use
CachePlugin::clientCache($pool, $streamFactory, $options); to cache
private responses or change
respect_response_cache_directives option to your needs.
It does store responses with cookies or a
Set-Cookie header. Be careful with
the order of your plugins.