Extending site configuration

Adding custom / project-specific options to site configuration

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

The site entity automatically provides the complete configuration via the getConfiguration() method, therefore extending that means "just add whatever you want to the YAML file". The GUI is built in a way that toplevel options that are unknown or not available in the form are left alone and will not get overwritten when saved.


config/sites/<some_site>/config.yaml | typo3conf/sites/<some_site>/config.yaml
rootPageId: 1
base: https://example.org/
  recordStorage: 15

Access it via the API:


Extending the form / GUI

Extending the GUI is a bit more tricky.

The backend module relies on form engine 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 form engine code.

The render configuration is stored in EXT:backend/Configuration/SiteConfiguration/ (GitHub) 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.

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, FlexForm handling and similar.

The example below shows the experimental feature adding a field to site in an extension's Configuration/SiteConfiguration/Overrides/sites.php file. 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 its value stored in the config.yaml file. Using the site object \TYPO3\CMS\core\Site\Entity\Site, the value can be fetched using ->getConfiguration()['myNewField'].