Feature toggle API

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:

$GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['myFeatureName'] ??= true; // or false;

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

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
        }

        // ...
    }
}

$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:

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

'SYS' => [
    'features' => [
        'redirects.hitCount' => true,
    ],
]

Feature toggles in TypoScript

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

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

Feature toggles in Fluid

The Feature ViewHelper <f:feature> can be used to check for a feature in a Fluid template:

<f:feature name="unifiedPageTranslationHandling">
   This is being shown if the flag is enabled
</f:feature>