LanguageNegotiatorInterface

Common interface for language negotiation services.

The language negotiation API is based on two major concepts:

• Language types: types of translatable data (the types of data that a user can view or request).
• Language negotiation methods: responsible for determining which language to use to present a particular piece of data to the user.

Both language types and language negotiation methods are customizable.

Drupal defines three built-in language types:

• Interface language: The page's main language, used to present translated user interface elements such as titles, labels, help text, and messages.
• Content language: The language used to present content that is available in more than one language.
• URL language: The language associated with URLs. When generating a URL, this value will be used for URL's as a default if no explicit preference is provided.

Modules can define additional language types through hook_language_types_info(), and alter existing language type definitions through hook_language_types_info_alter().

Language types may be configurable or fixed. The language negotiation methods associated with a configurable language type can be explicitly set through the user interface. A fixed language type has predetermined (module-defined) language negotiation settings and, thus, does not appear in the configuration page. Here is a code snippet that makes the content language (which by default inherits the interface language's values) configurable:

function mymodule_language_types_info_alter(&$language_types) {
  unset($language_types[LanguageInterface::TYPE_CONTENT]['fixed']);
}

The locked configuration property prevents one language type from being switched from customized to not customized, and vice versa.

Every language type can have a different set of language negotiation methods assigned to it. Different language types often share the same language negotiation settings, but they can have independent settings if needed. If two language types are configured the same way, their language switcher configuration will be functionally identical and the same settings will act on both language types.

Drupal defines the following built-in language negotiation methods:

• URL: Determine the language from the URL (path prefix or domain).
• Session: Determine the language from a request/session parameter.
• User: Follow the user's language preference.
• User admin language: Identify admin language from the user preferences.
• Browser: Determine the language from the browser's language settings.
• Selected language: Use the default site language.

Language negotiation methods are simple plugin classes that implement a particular logic to return a language code. For instance, the URL method searches for a valid path prefix or domain name in the current request URL. If a language negotiation method does not return a valid language code, the next method associated with the language type (based on method weight) is invoked.

Modules can define additional language negotiation methods by simply provide the related plugins, and alter existing methods through hook_language_negotiation_info_alter(). Here is an example snippet that lets path prefixes be ignored for administrative paths:

<?php
function mymodule_language_negotiation_info_alter(&$negotiation_info) {
  // Replace the original plugin with our own implementation.
  $method_id = \Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationUrl::METHOD_ID;
  $negotiation_info[$method_id]['class'] = 'Drupal\my_module\Plugin\LanguageNegotiation\MyLanguageNegotiationUrl';
}

class MyLanguageNegotiationUrl extends LanguageNegotiationUrl {
  public function getCurrentLanguage(Request $request = NULL) {
    if ($request) {
      // Use the original URL language negotiation method to get a valid
      // language code.
      $langcode = parent::getCurrentLanguage($request);

      // If we are on an administrative path, override with the default
      language.
      if ($request->query->has('q') && strtok($request->query->get('q'), '/') == 'admin') {
        return $this->languageManager->getDefaultLanguage()->getId();
      }
      return $langcode;
    }
  }
}
?>
?>

For more information, see Language Negotiation API

Hierarchy

• interface \Drupal\language\LanguageNegotiatorInterface

See also

\Drupal\language\LanguageNegotiator::updateConfiguration()

File

core/modules/language/src/LanguageNegotiatorInterface.php, line 100

Namespace

Drupal\language

Members