fix(caching): Support page caching of GET requests (#1197)

Author: larowlan

graphql.services.yml

@@ -68,6 +68,14 @@ services:
     class: Drupal\graphql\GraphQL\Execution\ExecutorFactory
     arguments: ['@service_container']
 
+  # Deny caching of POST requests in the dynamic and standard page cache.
+  graphql.request_policy.deny_query:
+    public: false
+    class: Drupal\graphql\Cache\RequestPolicy\GetOnly
+    tags:
+      - { name: page_cache_request_policy }
+      - { name: dynamic_page_cache_request_policy }
+
   # Upcasting for graphql query request parameters.
   graphql.route_enhancer.query:
     class: Drupal\graphql\Routing\QueryRouteEnhancer

src/Cache/RequestPolicy/GetOnly.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Drupal\graphql\Cache\RequestPolicy;
+
+use Drupal\Core\PageCache\RequestPolicyInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Contains a request policy that prevents caching of non GET GraphQL requests.
+ */
+class GetOnly implements RequestPolicyInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function check(Request $request): ?string {
+    if ($request->attributes->has('_graphql') && $request->getMethod() !== Request::METHOD_GET) {
+      return static::DENY;
+    }
+    return NULL;
+  }
+
+}

src/RouteProvider.php

@@ -66,7 +66,6 @@ public function routes(): array {
         ])
         ->addOptions([
           '_auth' => $auth,
-          'no_cache' => TRUE,
           'default_url_options' => ['path_processing' => FALSE],
           'parameters' => ['graphql_server' => ['type' => 'entity:graphql_server']],
         ]);

tests/src/Kernel/Framework/ResultTest.php

@@ -3,6 +3,7 @@
 namespace Drupal\Tests\graphql\Kernel\Framework;
 
 use Drupal\Tests\graphql\Kernel\GraphQLTestBase;
+use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Test the whole query result pipeline.
@@ -29,10 +30,14 @@ protected function setUp(): void {
     $this->setUpSchema($schema);
 
     $this->mockResolver('Query', 'root', 'test');
+
+    $this->configureCachePolicy(900);
   }
 
   /**
    * Test a simple query result.
+   *
+   * @coversClass \Drupal\graphql\Cache\RequestPolicy\DenyPost
    */
   public function testQuery(): void {
     $result = $this->query('query { root }');
@@ -43,6 +48,24 @@ public function testQuery(): void {
         'root' => 'test',
       ],
     ], json_decode($result->getContent(), TRUE));
+    $this->assertTrue($result->isCacheable());
+    $this->assertEquals('max-age=900, public', $result->headers->get('Cache-Control'));
+  }
+
+  /**
+   * Test a simple POST query result.
+   *
+   * @coversClass \Drupal\graphql\Cache\RequestPolicy\DenyPost
+   */
+  public function testPostQuery(): void {
+    $result = $this->query('query { root }', NULL, [], NULL, FALSE, Request::METHOD_POST);
+    $this->assertSame(200, $result->getStatusCode());
+    $this->assertSame([
+      'data' => [
+        'root' => 'test',
+      ],
+    ], json_decode($result->getContent(), TRUE));
+    $this->assertFalse($result->isCacheable());
   }
 
   /**
@@ -67,6 +90,7 @@ public function testBatchedQueries(): void {
         ],
       ],
     ], json_decode($result->getContent(), TRUE));
+    $this->assertFalse($result->isCacheable());
   }
 
 }

tests/src/Kernel/GraphQLTestBase.php

@@ -3,6 +3,9 @@
 namespace Drupal\Tests\graphql\Kernel;
 
 use Drupal\Core\Cache\Cache;
+use Drupal\Core\PageCache\ChainRequestPolicy;
+use Drupal\Core\PageCache\RequestPolicy\NoSessionOpen;
+use Drupal\graphql\Cache\RequestPolicy\GetOnly;
 use Drupal\graphql\GraphQL\ResolverBuilder;
 use Drupal\KernelTests\KernelTestBase;
 use Drupal\language\Entity\ConfigurableLanguage;
@@ -87,6 +90,26 @@ protected function setUp(): void {
     $this->builder = new ResolverBuilder();
   }
 
+  /**
+   * Configures core's cache policy.
+   *
+   * Modifies the DefaultRequestPolicy classes, which always add in the
+   * CommandLineOrUnsafeMethod policy which will always result in DENY in a
+   * Kernel test because we're running via the command line.
+   *
+   * @param int $max_age
+   *   Max age to cache responses.
+   */
+  protected function configureCachePolicy(int $max_age = 900): void {
+    $this->container->set('dynamic_page_cache_request_policy', (new ChainRequestPolicy())
+      ->addPolicy(new GetOnly()));
+    $this->container->set('page_cache_request_policy', (new ChainRequestPolicy())
+      ->addPolicy(new NoSessionOpen($this->container->get('session_configuration')))
+      ->addPolicy(new GetOnly()));
+    // Turn on caching.
+    $this->config('system.performance')->set('cache.page.max_age', $max_age)->save();
+  }
+
   /**
    * Returns the default cache maximum age for the test.
    */

tests/src/Traits/HttpRequestTrait.php

@@ -31,11 +31,13 @@ trait HttpRequestTrait {
    *   The query extensions.
    * @param bool $persisted
    *   Flag if the query is actually the identifier of a persisted query.
+   * @param string $method
+   *   Method, GET or POST.
    *
    * @return \Symfony\Component\HttpFoundation\Response
    *   The http response object.
    */
-  protected function query($query, $server = NULL, array $variables = [], array $extensions = NULL, $persisted = FALSE) {
+  protected function query($query, $server = NULL, array $variables = [], array $extensions = NULL, $persisted = FALSE, string $method = Request::METHOD_GET) {
     $server = $server ?: $this->server;
     if (!($server instanceof Server)) {
       throw new \LogicException('Invalid server.');
@@ -46,10 +48,16 @@ protected function query($query, $server = NULL, array $variables = [], array $e
     // If the persisted flag is true, then instead of sending the full query to
     // the server we only send the query id.
     $query_key = $persisted ? 'queryId' : 'query';
-    $request = Request::create($endpoint, 'GET', [
+    $data = [
       $query_key => $query,
       'variables' => $variables,
-    ] + $extensions);
+    ] + $extensions;
+    if ($method === Request::METHOD_GET) {
+      $request = Request::create($endpoint, $method, $data);
+    }
+    else {
+      $request = Request::create($endpoint, $method, [], [], [], [], json_encode($data));
+    }
 
     return $this->container->get('http_kernel')->handle($request);
   }