Feature toggles

TYPO3 provides an API class for creating so-called "feature toggles". Feature toggles provide an easy way to add new implementations of features next to their legacy version. By using a feature toggle, the integrator or site administrator can decide when to switch to the new feature.

The API checks against a system-wide option array within $GLOBALS['TYPO3_CONF_VARS']['SYS']['features'] which an integrator or admininistrator can set in the config/system/settings.php file. Both TYPO3 Core and extensions can provide alternative functionality for a certain feature.

Examples for features are:

  • Throw exceptions in new code instead of just returning a string message as error message.

  • Disable obsolete functionality which might still be used, but slows down the system.

  • Enable alternative "page not found" handling for an installation.

Naming of feature toggles

Feature names should NEVER be named "enable" or have a negation, or contain versions or years. It is recommended to use "lowerCamelCase" notation for the feature names.

Bad examples:

  • enableFeatureXyz

  • disableOverlays

  • schedulerRevamped2018

  • useDoctrineQueries

  • disablePreparedStatements

  • disableHooksInFE

Good examples:

  • extendedRichtextFormat

  • nativeYamlParser

  • inlinePageTranslations

  • typoScriptParserIncludesAsXml

  • nativeDoctrineQueries

Using the API as extension author

For extension authors, the API can be used for any custom feature provided by an extension.

To register a feature and set the default state, add the following to the ext_localconf.php file of your extension:

EXT:some_extension/ext_localconf.php
$GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['myFeatureName'] ??= true; // or false;

To check if a feature is enabled, use this code:

EXT:some_extension/Classes/SomeClass.php
use TYPO3\CMS\Core\Configuration\Features;

final class SomeClass {
    public function __construct(
        private readonly Features $features,
    ) {
    }

    public function doSomething(): void
    {
        if ($this->features->isFeatureEnabled('myFeatureName') {
            // do custom processing
        }

        // ...
    }
}

Attention

Currently, only the Core features can be (de-)activated in the Install Tool.

To change the setting for your extension feature either use config/system/settings.php or config/system/additional.php files like:

config/system/additional.php | typo3conf/system/additional.php
$GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['myFeatureName'] = true;

The name can be any arbitrary string, but an extension author should prefix the feature with the extension name as the features are global switches which otherwise might lead to naming conflicts.

Core feature toggles

Some examples for feature toggles in the TYPO3 Core:

  • redirects.hitCount: Enables hit statistics in the redirects backend module

  • security.backend.enforceReferrer: If on, HTTP referrer headers are enforced for backend and install tool requests to mitigate potential same-site request forgery attacks.

Enable / disable feature toggle

Features can be toggled in the Admin Tools > Settings module via Feature Toggles:

../_images/FeatureToggles.png

Internally, the changes are written to config/system/settings.php:

config/system/settings.php
'SYS' => [
    'features' => [
        'redirects.hitCount' => true,
    ],
]

Note

New in version 12.1.

If the config/system/settings.php file is write-protected an info box is rendered. In that case, all input fields are disabled and the save button is not available.

Feature toggles in TypoScript

One can check whether a feature is enabled in TypoScript with the function feature():

EXT:some_extension/Configuration/TypoScript/setup.typoscript
[feature("unifiedPageTranslationHandling")]
    # This condition matches if the feature toggle "unifiedPageTranslationHandling" is true
[END]

[feature("unifiedPageTranslationHandling") === false]
    # This condition matches if the feature toggle "unifiedPageTranslationHandling" is false
[END]