Routing for controller with multilingual enabled

Question

On my Drupal 8 multilingual project, I have made a custom controller which create a basic page, but I can't figure out which parameter I must use in the routing. Is this _locale?

This is the definition of the route.

custom.route:
path: '{_locale}/portail'
defaults:
  _content: '\Drupal\my_module\Controller\DisplayController::display'
requirements:
_access: 'TRUE

This is the code I am using in the controller class.

public function display(Request $request, $locale) {
    var_dump($locale);die;
}

Answer 1

The language is detected and the prefix removed before routing. So you have a static route without parameter and in the controller you can get the prefix from the language manager:

  $langcode = $this->languageManager()->getCurrentLanguage()->getId();

Answer 2

To those like @liquidcms wondering how to do a multilingual path : you can make as many routes as languages, to the same controller.

custom.route.lang_one:
  path: '/path/in/this/language'
  defaults:
    _controller: '\Drupal\my_module\Controller\MyController::method'
  requirements:
    _permission: 'access content'

custom.route.lang_two:
  path: '/path/in/that/other/language'
  defaults:
    _controller: '\Drupal\my_module\Controller\MyController::method'
  requirements:
    _permission: 'access content'

And then you check the language in the controller as already mentioned by @4k4.

Answer 3

One controller with a single route, different paths in different languages:

my_module.routing.yml

custom.route:
  path: '/path-english'
  defaults:
    _controller: '\Drupal\my_module\Controller\MyController::method'
  requirements:
    _permission: 'access content'

This works for english (default language), but say we want /path-deutsch in German. We need to manipulate the path using a PathProcessor.

Set up the service in my_module.services.yml:

services:
  my_module.path_processor:
    class: Drupal\my_module\Path\PathProcessor
    arguments: ['@language_manager']
    tags:
      - { name: path_processor_inbound, priority: 50 }
      - { name: path_processor_outbound, priority: 50 }

The class is inmy_module/src/Path/PathProcessor.php:

<?php

namespace Drupal\my_module\Path;

use Drupal\Core\Language\LanguageManagerInterface;
use Drupal\Core\PathProcessor\InboundPathProcessorInterface;
use Drupal\Core\PathProcessor\OutboundPathProcessorInterface;
use Drupal\Core\Render\BubbleableMetadata;
use Symfony\Component\HttpFoundation\Request;

/**
 * Rewrites inbound and outbound paths.
 */
class PathProcessor implements InboundPathProcessorInterface, OutboundPathProcessorInterface {

  /**
   * @var \Drupal\Core\Language\LanguageManagerInterface
   */
  protected $languageManager;

  /**
   * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
   */
  public function __construct(LanguageManagerInterface $language_manager) {
    $this->languageManager = $language_manager;
  }

  /**
   * {@inheritdoc}
   */
  public function processInbound($path, Request $request) {
    if ($this->languageManager->getCurrentLanguage()->getId() === 'de' && $path === '/path-deutsch') {
      return '/path-english';
    }

    return $path;
  }

  /**
   * {@inheritdoc}
   */
  public function processOutbound($path, &$options = [], Request $request = NULL, BubbleableMetadata $bubbleable_metadata = NULL) {
    if ($path === '/path-english') {
      if ($options['language']->getId() === 'de') {
        return '/path-deutsch';
      }
    }

    return $path;
  }

}

processInbound rewrites the German path in the request to the route used by the controller.

processOutbound ensures that any generated links in a German context use the correct German path. (This doesn't work if you use two separate controller routes.)

// Will return '/path-deutsch'.  
$url = Url::fromRoute('custom.route', ['language' => 'de'])->toString();

This means that the language switcher block etc. will automatically use the correct path.