Throw 404 when visited entity is not in current language

src/Controller/FrontController.php

@@ -26,22 +26,34 @@ class FrontController extends ControllerBase
     /** @var Dispatcher */
     protected $dispatcher;
 
+    /** @var array */
+    protected $settings;
+
+    protected $throw404WhenNotTranslated = true;
+
     public function __construct(
         ArgumentResolverInterface $argumentResolver,
         ControllerResolverInterface $controllerResolver,
-        Dispatcher $dispatcher
+        Dispatcher $dispatcher,
+        array $settings
     ) {
         $this->argumentResolver = $argumentResolver;
         $this->dispatcher = $dispatcher;
         $this->controllerResolver = $controllerResolver;
+        $this->settings = $settings;
+
+        if (isset($this->settings['404_when_not_translated'])) {
+            $this->throw404WhenNotTranslated = $this->settings['404_when_not_translated'];
+        }
     }
 
     public static function create(ContainerInterface $container)
     {
         return new static(
             $container->get('http_kernel.controller.argument_resolver'),
             $container->get('controller_resolver'),
-            $container->get('wmcontroller.cache.dispatcher')
+            $container->get('wmcontroller.cache.dispatcher'),
+            $container->getParameter('wmcontroller.settings'),
         );
     }
 
@@ -60,6 +72,7 @@ public function node(Request $request, EntityInterface $node)
      */
     protected function forward(Request $request, EntityInterface $entity)
     {
+        $this->validateLangcode($entity);
         $this->request = $request;
 
         $controller = [$this->getController($entity), 'show'];
@@ -117,5 +130,19 @@ protected function camelize($input, $separator = '_')
     {
         return str_replace($separator, '', ucwords($input, $separator));
     }
+
+    protected function validateLangcode(EntityInterface $entity)
+    {
+        $langcode = $this->languageManager()->getCurrentLanguage()->getId();
+        $isMultiLang = count($this->languageManager()->getLanguages()) > 1;
+
+        if (
+            $isMultiLang
+            && $this->throw404WhenNotTranslated
+            && $entity->language()->getId() !== $langcode
+        ) {
+            throw new NotFoundHttpException();
+        }
+    }
 }
 

src/EventSubscriber/InjectFrontControllerRouteSubscriber.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\wmcontroller\EventSubscriber;
 
+use Drupal\wmcontroller\Controller\FrontController;
 use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
 use Drupal\Core\Routing\RoutingEvents;
@@ -15,6 +16,8 @@ class InjectFrontControllerRouteSubscriber extends RouteSubscriberBase
 {
     protected $settings;
 
+    protected $frontController = FrontController::class;
+
     public function __construct(array $settings)
     {
         if (empty($settings['module'])) {
@@ -23,6 +26,10 @@ public function __construct(array $settings)
             );
         }
 
+        if (isset($settings['frontcontroller'])) {
+            $this->frontController = $settings['frontcontroller'];
+        }
+
         $this->settings = $settings;
     }
 
@@ -69,8 +76,8 @@ protected function alterRoute(Route $route, $controllerMethod)
         // The FrontController will delegate to a bundle-specific controller
         $defaults['_controller'] = sprintf(
             '%s%s%s',
-            $this->settings['frontcontroller'],
-            class_exists($this->settings['frontcontroller'])
+            $this->frontController,
+            class_exists($this->frontController)
                 ? '::' // FQN::method
                 : ':', // servicename:method
             $controllerMethod

wmcontroller.services.yml

@@ -18,6 +18,11 @@ parameters:
         # The controller responsible for forwarding to bundle-specific controllers
         frontcontroller: 'Drupal\wmcontroller\Controller\FrontController'
 
+        # Throw a 404 NotFoundHttpException when an entity is not translated
+        # in the current language. ( /en/node/123 gives 404 if node/123 has no
+        # en translation )
+        404_when_not_translated: true
+
     # Expiry rules.
     # maxage = client side caching duration
     # s-maxage = server side caching duration (this can be drupal db or a cdn)