Adding entity query example.

Author: fubhy

examples/graphql/example.graphqls

@@ -4,10 +4,19 @@ schema {
 
 type Query {
   article(id: Int!): Article
+  articles(
+    offset: Int = 0
+    limit: Int = 10
+  ): ArticleConnection!
 }
 
 type Article {
   id: Int!
   title: String!
   author: String
 }
+
+type ArticleConnection {
+  total: Int!
+  items: [Article!]
+}

examples/src/Plugin/GraphQL/DataProducer/QueryArticles.php

@@ -0,0 +1,108 @@
+<?php
+
+namespace Drupal\graphql_examples\Plugin\GraphQL\DataProducer;
+
+use Drupal\Core\Cache\RefinableCacheableDependencyInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\graphql\Plugin\GraphQL\DataProducer\DataProducerPluginBase;
+use Drupal\graphql_examples\Wrappers\QueryConnection;
+use GraphQL\Error\UserError;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * @DataProducer(
+ *   id = "query_articles",
+ *   name = @Translation("Load articles"),
+ *   description = @Translation("Loads a list of articles."),
+ *   produces = @ContextDefinition("any",
+ *     label = @Translation("Article connection")
+ *   ),
+ *   consumes = {
+ *     "offset" = @ContextDefinition("integer",
+ *       label = @Translation("Offset"),
+ *       required = FALSE
+ *     ),
+ *     "limit" = @ContextDefinition("integer",
+ *       label = @Translation("Limit"),
+ *       required = FALSE
+ *     )
+ *   }
+ * )
+ */
+class QueryArticles extends DataProducerPluginBase implements ContainerFactoryPluginInterface {
+
+  const MAX_LIMIT = 100;
+
+  /**
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityManager;
+
+  /**
+   * {@inheritdoc}
+   *
+   * @codeCoverageIgnore
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('entity.manager')
+    );
+  }
+
+  /**
+   * Articles constructor.
+   *
+   * @param array $configuration
+   *   The plugin configuration.
+   * @param string $pluginId
+   *   The plugin id.
+   * @param mixed $pluginDefinition
+   *   The plugin definition.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entityManager
+   *
+   * @codeCoverageIgnore
+   */
+  public function __construct(
+    array $configuration,
+    $pluginId,
+    $pluginDefinition,
+    EntityTypeManagerInterface $entityManager
+  ) {
+    parent::__construct($configuration, $pluginId, $pluginDefinition);
+    $this->entityManager = $entityManager;
+  }
+
+  /**
+   * @param $offset
+   * @param $limit
+   * @param \Drupal\Core\Cache\RefinableCacheableDependencyInterface $metadata
+   *
+   * @return \Drupal\graphql_examples\Wrappers\QueryConnection
+   * @throws \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException
+   * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
+   */
+  public function resolve($offset, $limit, RefinableCacheableDependencyInterface $metadata) {
+    if (!$limit > static::MAX_LIMIT) {
+      throw new UserError(sprintf('Exceeded maximum query limit: %s.', static::MAX_LIMIT));
+    }
+
+    $storage = $this->entityManager->getStorage('node');
+    $type = $storage->getEntityType();
+    $query = $storage->getQuery()
+      ->currentRevision()
+      ->accessCheck();
+
+    $query->condition($type->getKey('bundle'), 'article');
+    $query->range($offset, $limit);
+
+    $metadata->addCacheTags($type->getListCacheTags());
+    $metadata->addCacheContexts($type->getListCacheContexts());
+
+    return new QueryConnection($query);
+  }
+}

examples/src/Plugin/GraphQL/Schema/ExampleSchema.php

@@ -5,6 +5,7 @@
 use Drupal\graphql\GraphQL\ResolverBuilder;
 use Drupal\graphql\GraphQL\ResolverRegistry;
 use Drupal\graphql\Plugin\GraphQL\Schema\SdlSchemaPluginBase;
+use Drupal\graphql_examples\Wrappers\QueryConnection;
 
 /**
  * @Schema(
@@ -23,6 +24,7 @@ public function getResolverRegistry() {
 
     $this->addQueryFields($registry, $builder);
     $this->addArticleFields($registry, $builder);
+    $this->addArticleConnectionFields($registry, $builder);
 
     return $registry;
   }
@@ -67,5 +69,29 @@ protected function addQueryFields(ResolverRegistry $registry, ResolverBuilder $b
         ->map('bundles', $builder->fromValue(['article']))
         ->map('id', $builder->fromArgument('id'))
     );
+
+    $registry->addFieldResolver('Query', 'articles',
+      $builder->produce('query_articles')
+        ->map('offset', $builder->fromArgument('offset'))
+        ->map('limit', $builder->fromArgument('limit'))
+    );
+  }
+
+  /**
+   * @param \Drupal\graphql\GraphQL\ResolverRegistry $registry
+   * @param \Drupal\graphql\GraphQL\ResolverBuilder $builder
+   */
+  protected function addArticleConnectionFields(ResolverRegistry $registry, ResolverBuilder $builder) {
+    $registry->addFieldResolver('ArticleConnection', 'total',
+      $builder->callback(function (QueryConnection $connection) {
+        return $connection->total();
+      })
+    );
+
+    $registry->addFieldResolver('ArticleConnection', 'items',
+      $builder->callback(function (QueryConnection $connection) {
+        return $connection->items();
+      })
+    );
   }
 }

examples/src/Wrappers/QueryConnection.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace Drupal\graphql_examples\Wrappers;
+
+use Drupal\Core\Entity\Query\QueryInterface;
+use GraphQL\Deferred;
+
+class QueryConnection {
+
+  /**
+   * @var \Drupal\Core\Entity\Query\Sql\Query
+   */
+  protected $query;
+
+  /**
+   * QueryConnection constructor.
+   *
+   * @param \Drupal\Core\Entity\Query\QueryInterface $query
+   */
+  public function __construct(QueryInterface $query) {
+    $this->query = $query;
+  }
+
+  /**
+   * @return int
+   */
+  public function total() {
+    $query = clone $this->query;
+    $query->range(NULL, NULL)->count();
+    return $query->execute();
+  }
+
+  /**
+   * @return array|\GraphQL\Deferred
+   */
+  public function items() {
+    $result = $this->query->execute();
+    if (empty($result)) {
+      return [];
+    }
+
+    $buffer = \Drupal::service('graphql.buffer.entity');
+    $callback = $buffer->add($this->query->getEntityTypeId(), array_values($result));
+    return new Deferred(function () use ($callback) {
+      return $callback();
+    });
+  }
+}