Developer Information

This chapter is targeted at extension authors who want to use the caching framework for their needs. It is about how to use the framework properly. For details about its inner working, please refer to the section about architecture.

Example usages can be found throughout the TYPO3 Core, in particular in the system extensions core and extbase.

Cache Registration

Registration of a new cache should be done in an extension's ext_localconf.php. The example below defines an empty sub-array in cacheConfigurations. Neither frontend nor backend are defined: The cache manager will choose the default variable frontend and the database backend by default.

EXT:my_extension/ext_localconf.php
$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['myext_mycache']
    ??= [];

Tip

The null coalescing assignment operator (??=) check is used to enable administrators to overwrite configuration of caches in config/system/settings.php. During bootstrap, any ext_localconf.php is loaded after config/system/settings.php and config/system/additional.php are loaded, so it is important to make sure that the administrator did not already set any configuration of the extensions cache.

If special settings are needed, for example a specific backend (like the transient memory backend), it can be defined with an additional line below the cache array declaration. The extension documentation should hint an integrator about specific caching needs or setups in this case.

Tip

Extensions should not force specific settings, therefore the null coalescing assignment operator (??=) is used to allow administrators to overwrite those settings. It is recommended to set up a cache configuration with sane defaults, but administrators should always be able to overwrite them for whatever reason.

EXT:my_extension/ext_localconf.php
// use \TYPO3\CMS\Core\Cache\Backend\TransientMemoryBackend;
$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['myext_mycache']
    ??= [];
$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['myext_mycache']['backend']
    ??= TransientMemoryBackend::class;

Using the Cache

First, we need to prepare injection of our cache by setting it up as service in the container service configuration:

EXT:my_extension/Configuration/Services.yaml
services:
  _defaults:
    autowire: true
    autoconfigure: true
    public: false

  Vendor\MyExtension\:
    resource: '../Classes/*'

  cache.myext_mycache:
    class: TYPO3\CMS\Core\Cache\Frontend\FrontendInterface
    factory: ['@TYPO3\CMS\Core\Cache\CacheManager', 'getCache']
    arguments: ['myext_mycache']

The name of the service for the injection configuration is cache.myext_mycache, the name of the cache is myext_mycache (as defined in ext_localconf.php). Both can be anything you like, just make sure they are unique and clearly hint at the purpose of your cache.

Here is some example code which retrieves the cache via dependency injection:

EXT:my_extension/Classes/MyClass.php
namespace Vendor\MyExtension;

use TYPO3\CMS\Core\Cache\Frontend\FrontendInterface;

class MyClass
{
    public function __construct(
        private readonly FrontendInterface $cache
    )
    {
    }

    private function getCachedValue()
    {
        $cacheIdentifier = /* ... logic to determine the cache identifier ... */;

        // If value is false, it has not been cached
        $value = $this->cache->get($cacheIdentifier);
        if ($value === false) {
            // Calculate the value and store it in the cache
            $value = /* ... Logic to calculate value ... */;
            $tags = /* ... Tags for the cache entry ... */;
            $lifetime = /* ... Calculate/define cache entry lifetime ... */;

            // Store value in cache
            $this->cache->set($cacheIdentifier, $value, $tags, $lifetime);
        }

        return $value;
    }

Tip

It is not needed to call $this->cache->has() before accessing cache entries with $this->cache->get() as the latter returns false if no entry exists.

Since the auto-wiring feature of the dependency injection container cannot detect which cache configuration should be used for the $cache argument of MyClass, the container service configuration needs to be extended:

EXT:my_extension/Configuration/Services.yaml
services:
  # other configurations

  Vendor\MyExtension\MyClass:
    arguments:
      $cache: '@cache.myext_mycache'

Here @cache.myext_mycache refers to the cache service we defined above. This setup allows you to freely inject the very same cache into any class.

Note

After changes in the Services.yaml file flush the cache via Admin Tools > Maintenance or the CLI command cache:flush:

vendor/bin/typo3 cache:flush