interface 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.

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 getLangcode(Request $request = NULL) {
    if ($request) {
      // Use the original URL language negotiation method to get a valid
      // language code.
      $langcode = parent::getLangcode($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

Expanded class hierarchy of LanguageNegotiatorInterface

All classes that implement LanguageNegotiatorInterface

See also

\Drupal\language\LanguageNegotiator::updateConfiguration()

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:

File

core/modules/language/src/LanguageNegotiatorInterface.php, line 99

Namespace

interface LanguageNegotiatorInterface {
    
    /**
     * The language negotiation method id for the language negotiator itself.
     */
    const METHOD_ID = 'language-default';
    
    /**
     * Resets the negotiated languages and the method instances.
     */
    public function reset();
    
    /**
     * Sets the current active user and resets all language types.
     *
     * @param \Drupal\Core\Session\AccountInterface $current_user
     *   The current active user.
     */
    public function setCurrentUser(AccountInterface $current_user);
    
    /**
     * Initializes the specified language type.
     *
     * @param string $type
     *   The language type to be initialized.
     *
     * @return \Drupal\Core\Language\LanguageInterface[]
     *   Returns an array containing a single language keyed by the language
     *   negotiation method ID used to determine the language of the specified
     *   type. If negotiation is not possible the default language is returned.
     */
    public function initializeType($type);
    
    /**
     * Returns the language negotiation methods enabled for a language type.
     *
     * @param string $type
     *   (optional) The language type. If no type is specified all the method
     *   definitions are returned.
     *
     * @return array[]
     *   An array of language negotiation method definitions keyed by method id.
     */
    public function getNegotiationMethods($type = NULL);
    
    /**
     * Returns an instance of the specified language negotiation method.
     *
     * @param string $method_id
     *   The method identifier.
     *
     * @return \Drupal\language\LanguageNegotiationMethodInterface
     */
    public function getNegotiationMethodInstance($method_id);
    
    /**
     * Returns the ID of the language type's primary language negotiation method.
     *
     * @param string $type
     *   The language type.
     *
     * @return string
     *   The identifier of the primary language negotiation method for the given
     *   language type, or the default method if none exists.
     */
    public function getPrimaryNegotiationMethod($type);
    
    /**
     * Checks whether a language negotiation method is enabled for a language type.
     *
     * @param string $method_id
     *   The language negotiation method ID.
     * @param string $type
     *   (optional) The language type. If none is passed, all the configurable
     *   language types will be inspected.
     *
     * @return bool
     *   TRUE if the method is enabled for at least one of the given language
     *   types, or FALSE otherwise.
     */
    public function isNegotiationMethodEnabled($method_id, $type = NULL);
    
    /**
     * Saves a list of language negotiation methods for a language type.
     *
     * @param string $type
     *   The language type.
     * @param int[] $enabled_methods
     *   An array of language negotiation method weights keyed by method ID.
     */
    public function saveConfiguration($type, $enabled_methods);
    
    /**
     * Resave the configuration to purge missing negotiation methods.
     */
    public function purgeConfiguration();
    
    /**
     * Updates the configuration based on the given language types.
     *
     * Stores the list of the language types along with information about their
     * configurable state. Stores the default settings if the language type is
     * not configurable.
     *
     * @param string[] $types
     *   An array of configurable language types.
     */
    public function updateConfiguration(array $types);

}

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