Programmatically get menu links filtered by language

Question

In Drupal 8, I'm trying to get my menu which has translated menu item filtered by a given language.

So far, I was able to get my menu tree :

    $menu_parameters = $this->menuLinkTree->getCurrentRouteMenuTreeParameters('main');
    $menu_tree = $this->menuLinkTree->load('main', $menu_parameters);
    $manipulators = array(
        // Only show links that are accessible for the current user.
        array('callable' => 'menu.default_tree_manipulators:checkAccess'),
        // Use the default sorting of menu links.
        array('callable' => 'menu.default_tree_manipulators:generateIndexAndSort'),
    );
    $menu_tree = $this->menuLinkTree->transform($menu_tree, $manipulators);

But I still have "stand alone" links in both language.

I looked into manipulators and parameters, but couldn't see anything related to translation.

Maybe using MenuTreeParameters::addCondition, but i'm missing something here.

Any help would be greatly appreciated.

Answer 1

@pbonnefoi. I've played a lot around with a filtering of menu items by language while worked on menu block multilingual task.

Here what I got:
Drupal\menu_link_content\Plugin\Menu\MenuLinkContent is responsible for retrieving of menu_link entity, but this class hides from us getEntity() method, using one we could get menu link language ($link->getEntity()->get('langcode'))

So the trick is:

1. Extend this plugin by a new method getLanguage() and register it.
   This plugin used in the menu.tree_storage service, also you need to change link provider class and plugin class to yours.

2. Create a new manipulator yourmodule.menu_manipulators:filterByLang,
   and use it wherever you want like:
   ['callable' => 'yourmodule.menu_manipulators:filterByLang', 'args' => ['langcode' => $langcode]]

Result code can be something like:

class MenuMultilingualServiceProvider extends ServiceProviderBase {

  public function alter(ContainerBuilder $container) {
    $definition = $container->getDefinition('menu.tree_storage');
    $definition->setClass('Drupal\yourmodule\Menu\MenuTreeStorageMultilingual');
  }
}

class MenuTreeStorageMultilingual extends MenuTreeStorage {
  protected function doCollectRoutesAndDefinitions(array $tree, array &$definitions) {
    foreach ($definitions as &$definition) {
      if ($definition['provider'] == 'menu_link_content') {
        $definition['class'] = 'Drupal\yourmodule\Plugin\Menu\MenuLinkContentMultilingual';
      }
    }
    return parent::doCollectRoutesAndDefinitions($tree, $definitions);
  }

  protected function loadLinks($menu_name, MenuTreeParameters $parameters) {
    $links = parent::loadLinks($menu_name, $parameters);
    foreach ($links as &$link) {
      if ($link['provider'] == 'menu_link_content') {
        $link['class'] = 'Drupal\yourmodule\Plugin\Menu\MenuLinkContentMultilingual';
      }
    }
    return $links;
  }

}

UPDATE: Also tuutti created another solution for that using a new menu tree manipulator menu_block_current_language_tree_manipulator::filterLanguages inside a new menu block type.

Here is his sandbox https://www.drupal.org/sandbox/tuutti/2832329

Also welcome to the discussion regarding translatable menu links on the d.o https://www.drupal.org/node/2466553

UPDATE 2: I've created a module for the end user to bring multilingual features to the menu blocks https://www.drupal.org/sandbox/matsbla/2831709

You can refer to it as an example of all said above.