Contextual language handling. (#550)

* Intermediate commit, not functional.

* Don't abort context retrieval on falsy path elements.

* Removed all implicit language contexts.

* Contextual language negotiation.

* Enforcing graphql language negotiation through config overrides.

* Fixing language negotiator.

* Fixed negotiation.

* Ignore language cache contexts.

* Added upgrade instructions for languages.

* Docs fix.

* Fix to also work without language module enabled.

* Fixed wrong return, has to be yield.

* Added core 8.5 tests.

* Docs fix.

* Moved contextual language to service.

* Travis debug.

* Removed travis debug.

* Renamed test class according to file.

* More tests and resulting fixes.

* Simplified language context.

* Explicit callable execution.

* More fine grained tests.

* Test negotiator initialization result.

* Test cleanup.

* Test disable negotiator fix.

* Debugging ...

* Debugging ...

* Debugging ...

* Debugging ...

* Check negotiator instance.

* Changed module initialization order.

* Depending on language module.

* Revert "Depending on language module."

This reverts commit f8df099

* Revert "Changed module initialization order."

This reverts commit bbaa77f

* Proper service provider classname.

* Properly injecting the language context.

* Annotation style fixes.

* Revert "Properly injecting the language context."

This reverts commit c358b53

* Real setter injection.

* Moved property to top.

* Use language cache contexts to conditionally set the graphql language context.

* Enabled multilingual features for all tests to catch potential context leaks.

* Ignore language contexts when creating the cache key.

* Reproducing leaking translation context.

* Add language_content cache context to RouteEntity since the access
handler emits it for some reason.

* Fixed exception expectation.

Author: pmelab

doc/upgrade/beta6.md

@@ -2,6 +2,33 @@
 ## Schema changes
 These changes affect you if you are using the schema automatically generated by the `graphql_core` module.
 
+
+### Language handling
+
+Multilingual queries changed drastically. The endpoints language negotiation is ignored entirely, instead all language handling is left to the query and its arguments. A couple of fields accept a "language" argument, and whenever this argument is filled explicitly, it's value will be inherited to subsequent occurrences. The `route` field will set this context implicitly from the paths language prefix.
+
+```graphql
+query {
+  route(path: "/node/1") {
+    ... on EntityCanonicalUrl {
+      entity {
+        # Will emit the default language.
+        entityLabel
+      }
+    }
+  }
+  route(path: "/fr/node/1") {
+    ... on EntityCanonicalUrl {
+      entity {
+        # Will emit the french translation.
+        entityLabel
+      }
+    }
+  }
+}
+
+```
+
 ### Url Interfaces
 The type structure of the `Url` object changed. While before there have been just the `InternalUrl` and `ExternalUrl` types, the `InternalUrl` has become an interface that can resolve to different Url types, depending on the underlying route. The `DefaultInternalUrl` has the fields for context resolving and other generic rout information. The `EntityCanonicalUrl` has access to the underlying entity.
 

graphql.services.yml

@@ -244,8 +244,19 @@ services:
 
   # Buffers.
   graphql.buffer.entity:
-      class: Drupal\graphql\GraphQL\Buffers\EntityBuffer
-      arguments: ['@entity_type.manager']
+    class: Drupal\graphql\GraphQL\Buffers\EntityBuffer
+    arguments: ['@entity_type.manager']
   graphql.buffer.subrequest:
-      class: Drupal\graphql\GraphQL\Buffers\SubRequestBuffer
-      arguments: ['@http_kernel', '@request_stack']
+    class: Drupal\graphql\GraphQL\Buffers\SubRequestBuffer
+    arguments: ['@http_kernel', '@request_stack']
+
+  graphql.language_context:
+    class: Drupal\graphql\GraphQLLanguageContext
+    arguments: ['@language_manager']
+
+  graphql.config_factory_override:
+    class: Drupal\graphql\Config\GraphQLConfigOverrides
+    arguments: ['@config.storage']
+    tags:
+      - { name: config.factory.override, priority: -253 }
+

modules/graphql_core/src/Plugin/Deriver/Interfaces/EntityTypeDeriver.php

@@ -39,10 +39,6 @@ public function getDerivativeDefinitions($basePluginDefinition) {
         $derivative['response_cache_contexts'][] = 'user.node_grants:view';
       }
 
-      if ($type->isTranslatable()) {
-        $derivative['response_cache_contexts'][] = 'languages:language_content';
-      }
-
       $this->derivatives[$typeId] = $derivative;
     }
 

modules/graphql_core/src/Plugin/Deriver/Types/EntityBundleDeriver.php

@@ -90,10 +90,6 @@ public function getDerivativeDefinitions($basePluginDefinition) {
           $derivative['response_cache_contexts'][] = 'user.node_grants:view';
         }
 
-        if ($type->isTranslatable()) {
-          $derivative['response_cache_contexts'][] = 'languages:language_content';
-        }
-
         $this->derivatives[$typeId . '-' . $bundle] = $derivative;
       }
     }

modules/graphql_core/src/Plugin/Deriver/Types/EntityTypeDeriver.php

@@ -40,10 +40,6 @@ public function getDerivativeDefinitions($basePluginDefinition) {
         $derivative['response_cache_contexts'][] = 'user.node_grants:view';
       }
 
-      if ($type->isTranslatable()) {
-        $derivative['response_cache_contexts'][] = 'languages:language_content';
-      }
-
       $this->derivatives[$typeId] = $derivative;
     }
 

modules/graphql_core/src/Plugin/GraphQL/Fields/Entity/EntityById.php

@@ -6,6 +6,7 @@
 use Drupal\Core\Entity\EntityRepositoryInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\TypedData\TranslatableInterface;
 use Drupal\graphql\GraphQL\Buffers\EntityBuffer;
 use Drupal\graphql\GraphQL\Cache\CacheableValue;
 use Drupal\graphql\GraphQL\Execution\ResolveContext;
@@ -20,6 +21,7 @@
  *   arguments = {
  *     "id" = "String!"
  *   },
+ *   contextual_arguments = {"language"},
  *   deriver = "Drupal\graphql_core\Plugin\Deriver\Fields\EntityByIdDeriver"
  * )
  */
@@ -109,8 +111,8 @@ protected function resolveValues($value, array $args, ResolveContext $context, R
         $access = $entity->access('view', NULL, TRUE);
 
         if ($access->isAllowed()) {
-          if (isset($args['language']) && $args['language'] != $entity->language()->getId()) {
-            $entity = $this->entityRepository->getTranslationFromContext($entity, $args['language']);
+          if (isset($args['language']) && $args['language'] != $entity->language()->getId() && $entity instanceof TranslatableInterface) {
+            $entity = $entity->getTranslation($args['language']);
           }
 
           yield $entity->addCacheableDependency($access);

modules/graphql_core/src/Plugin/GraphQL/Fields/Entity/EntityRevisionById.php

@@ -7,6 +7,7 @@
 use Drupal\Core\Entity\EntityRepositoryInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\TypedData\TranslatableInterface;
 use Drupal\graphql\GraphQL\Cache\CacheableValue;
 use Drupal\graphql\GraphQL\Execution\ResolveContext;
 use Drupal\graphql\Plugin\GraphQL\Fields\FieldPluginBase;
@@ -20,6 +21,7 @@
  *   arguments = {
  *     "id" = "String!"
  *   },
+ *   contextual_arguments = {"language"},
  *   deriver = "Drupal\graphql_core\Plugin\Deriver\Fields\EntityRevisionByIdDeriver"
  * )
  */
@@ -98,8 +100,8 @@ protected function resolveValues($value, array $args, ResolveContext $context, R
     }
     /** @var \Drupal\Core\Access\AccessResultInterface $access */
     else if (($access = $entity->access('view', NULL, TRUE)) && $access->isAllowed()) {
-      if (isset($args['language']) && $args['language'] != $entity->language()->getId()) {
-        $entity = $this->entityRepository->getTranslationFromContext($entity, $args['language']);
+      if ($entity instanceof TranslatableInterface && isset($args['language']) && $args['language'] != $entity->language()->getId()) {
+        $entity = $entity->getTranslation($args['language']);
       }
 
       yield new CacheableValue($entity, [$access]);

modules/graphql_core/src/Plugin/GraphQL/Fields/Entity/EntityTranslation.php

@@ -68,7 +68,7 @@ public function __construct(array $configuration, $pluginId, $pluginDefinition,
    */
   public function resolveValues($value, array $args, ResolveContext $context, ResolveInfo $info) {
     if ($value instanceof EntityInterface && $value instanceof TranslatableInterface && $value->isTranslatable()) {
-      yield $this->entityRepository->getTranslationFromContext($value, $args['language']);
+      yield $value->getTranslation($args['language']);
     }
   }
 

modules/graphql_core/src/Plugin/GraphQL/Fields/Entity/EntityTranslations.php

@@ -72,7 +72,7 @@ public function resolveValues($value, array $args, ResolveContext $context, Reso
     if ($value instanceof ContentEntityInterface && $value instanceof TranslatableInterface && $value->isTranslatable()) {
       $languages = $value->getTranslationLanguages();
       foreach ($languages as $language) {
-        yield $this->entityRepository->getTranslationFromContext($value, $language->getId());
+        yield $value->getTranslation($language->getId());
       }
     }
   }

modules/graphql_core/src/Plugin/GraphQL/Fields/EntityFieldBase.php

@@ -3,6 +3,9 @@
 namespace Drupal\graphql_core\Plugin\GraphQL\Fields;
 
 use Drupal\Component\Render\MarkupInterface;
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\Entity;
+use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Field\FieldItemInterface;
 use Drupal\graphql\GraphQL\Execution\ResolveContext;
 use Drupal\graphql\Plugin\GraphQL\Fields\FieldPluginBase;
@@ -31,6 +34,10 @@ protected function resolveItem($item, array $args, ResolveContext $context, Reso
         $result = $type->serialize($result);
       }
 
+      if ($result instanceof ContentEntityInterface && $result->isTranslatable() && $language = $context->getContext('language', $info)) {
+        $result = $result->getTranslation($language);
+      }
+
       return $result;
     }
   }