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Extending Site Configuration

Adding Custom / Project Specific Options to Site Configuration

Site configuration is stored as yaml and provides per definition context independent configuration of a site. Especially when thinking about things like storage PIDs or general site specific settings, it makes sense to add them to the site configuration.


In "the old days" these kind of options were commonly stored in TypoScript or TSConfig or LocalConfiguration, all three being in some ways a bit unfortunate - parsing TypoScript while on CLI or using TSConfig made for the backend in frontend was no fun.

Adding project configuration to site configuration is easy: The site entity will automatically provide the complete configuration via getConfiguration(), extending that means therefore "just add whatever you want to the yaml file". The GUI is built in a way that toplevel options unknown / not available in the form will be left alone and do not get overwritten when saving.


rootPageId: 1
    recordStorage: 15

Access it via the API:


Extending the Form / GUI

Extending the GUI is a bit more tricky.

The backend module relies on FormEngine to render the edit interface. Since the form data is not stored in database records but in .yaml files, a couple of details have been extended of the default FormEngine code.

The render configuration is stored in typo3/sysext/backend/Configuration/SiteConfiguration/ in a format syntactically identical to TCA. However, this is not loaded into $GLOBALS['TCA'] scope, and only a small subset of TCA features is supported.

Extending site configuration is experimental and may change any time.

In practice the configuration can be extended, but only with very simple fields like the basic config type input, and even for this one not all features are possible, for example the eval options are limited. The code throws exceptions or just ignores settings it does not support. While some of the limits may be relaxed a bit over time, many will be kept. The goal is to allow developers to extend the site configuration with a couple of simple things like an input field for a Google API key. However it is not possible to extend with complex TCA like inline relations, database driven select fields, Flex Form handling and similar.

The example below shows the experimental feature adding a field to site in an extensions file Configuration/SiteConfiguration/Overrides/sites.php. Note the helper methods of class TYPO3\CMS\core\Utility\ExtensionManagementUtility can not be used.

// Experimental example to add a new field to the site configuration

// Configure a new simple required input field to site
$GLOBALS['SiteConfiguration']['site']['columns']['myNewField'] = [
    'label' => 'A new custom field',
    'config' => [
        'type' => 'input',
        'eval' => 'required',
// And add it to showitem
$GLOBALS['SiteConfiguration']['site']['types']['0']['showitem'] = str_replace(
    'base, myNewField, ',

The field will be shown in the edit form of the configuration module and it's value stored in the .yaml file. Using the site object TYPO3\CMS\core\Site\Entity\Site, the value can be fetched using ->getConfiguration()['myNewField'].