Issue #2378789 by Wim Leers: Views output cache is broken

core/modules/views/src/Plugin/views/cache/CachePluginBase.php

@@ -7,6 +7,7 @@
 
 namespace Drupal\views\Plugin\views\cache;
 
+use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Cache\Cache;
 use Drupal\views\Plugin\views\PluginBase;
 use Drupal\Core\Database\Query\Select;
@@ -142,8 +143,8 @@ public function cacheSet($type) {
         \Drupal::cache($this->resultsBin)->set($this->generateResultsKey(), $data, $this->cacheSetExpire($type), $this->getCacheTags());
         break;
       case 'output':
-        $this->gatherHeaders($this->view->display_handler->output);
         $this->storage['output'] = drupal_render($this->view->display_handler->output);
+        $this->gatherRenderMetadata($this->view->display_handler->output);
         \Drupal::cache($this->outputBin)->set($this->generateOutputKey(), $this->storage, $this->cacheSetExpire($type), $this->getCacheTags());
         break;
     }
@@ -178,9 +179,13 @@ public function cacheGet($type) {
           if (!$cutoff || $cache->created > $cutoff) {
             $this->storage = $cache->data;
 
-            $this->restoreHeaders();
+            $this->restoreRenderMetadata();
             $this->view->display_handler->output = array(
               '#attached' => &$this->view->element['#attached'],
+              '#cache' => [
+                'tags' => &$this->view->element['#cache']['tags'],
+              ],
+              '#post_render_cache' => &$this->view->element['#post_render_cache'],
               '#markup' => $cache->data['output'],
             );
 
@@ -226,60 +231,28 @@ public function postRender(&$output) { }
 
   /**
    * Start caching the html head.
-   *
-   * This takes a snapshot of the current system state so that we don't
-   * duplicate it. Later on, when gatherHeaders() is run, this information
-   * will be removed so that we don't hold onto it.
-   *
-   * @see _drupal_add_html_head()
    */
-  public function cacheStart() {
-    $this->storage['head'] = _drupal_add_html_head();
-  }
+  public function cacheStart() { }
 
   /**
-   * Gather the JS/CSS from the render array and the html head from band data.
+   * Gather bubbleable render metadata from the render array.
    *
    * @param array $render_array
    *   The view render array to collect data from.
    */
-  protected function gatherHeaders(array $render_array = []) {
-    // Simple replacement for head
-    if (isset($this->storage['head'])) {
-      $this->storage['head'] = str_replace($this->storage['head'], '', _drupal_add_html_head());
-    }
-    else {
-      $this->storage['head'] = '';
-    }
-
-    $this->storage['css'] = $render_array['#attached']['css'];
-    $this->storage['js'] = $render_array['#attached']['js'];
+  protected function gatherRenderMetadata(array $render_array = []) {
+    $this->storage['attachments'] = $render_array['#attached'];
+    $this->storage['postRenderCache'] = $render_array['#post_render_cache'];
+    $this->storage['cacheTags'] = $render_array['#cache']['tags'];
   }
 
   /**
-   * Restore out of band data saved to cache. Copied from Panels.
+   * Restore bubbleable render metadata.
    */
-  public function restoreHeaders() {
-    if (!empty($this->storage['head'])) {
-      _drupal_add_html_head($this->storage['head']);
-    }
-    if (!empty($this->storage['css'])) {
-      foreach ($this->storage['css'] as $args) {
-        $this->view->element['#attached']['css'][] = $args;
-      }
-    }
-    if (!empty($this->storage['js'])) {
-      foreach ($this->storage['js'] as $key => $args) {
-        if ($key !== 'settings') {
-          $this->view->element['#attached']['js'][] = $args;
-        }
-        else {
-          foreach ($args as $setting) {
-            $this->view->element['#attached']['js']['setting'][] = $setting;
-          }
-        }
-      }
-    }
+  public function restoreRenderMetadata() {
+    $this->view->element['#attached'] = drupal_merge_attached($this->view->element['#attached'], $this->storage['attachments']);
+    $this->view->element['#cache']['tags'] = Cache::mergeTags(isset($this->view->element['#cache']['tags']) ? $this->view->element['#cache']['tags'] : [], $this->storage['cacheTags']);
+    $this->view->element['#post_render_cache'] = NestedArray::mergeDeep(isset($this->view->element['#post_render_cache']) ? $this->view->element['#post_render_cache'] : [], $this->storage['postRenderCache']);
   }
 
   /**

core/modules/views/src/Tests/Plugin/CacheTest.php

@@ -147,39 +147,14 @@ function testHeaderStorage() {
     $view->setDisplay();
     $output = $view->preview();
     drupal_render($output);
+    $this->assertTrue(in_array('views_test_data/test', $output['#attached']['library']), 'Make sure libraries are added for cached views.');
     $css_path = drupal_get_path('module', 'views_test_data') . '/views_cache.test.css';
     $js_path = drupal_get_path('module', 'views_test_data') . '/views_cache.test.js';
     $this->assertTrue(in_array($css_path, $output['#attached']['css']), 'Make sure the css is added for cached views.');
     $this->assertTrue(in_array($js_path, $output['#attached']['js']), 'Make sure the js is added for cached views.');
+    $this->assertTrue(['views_test_data:1'], $output['#cache']['tags']);
+    $this->assertTrue(['views_test_data_post_render_cache' => [['foo' => 'bar']]], $output['#post_render_cache']);
     $this->assertFalse(!empty($view->build_info['pre_render_called']), 'Make sure hook_views_pre_render is not called for the cached view.');
-
-    // Now add some css/jss before running the view.
-    // Make sure that this css is not added when running the cached view.
-    $view->storage->set('id', 'test_cache_header_storage_2');
-    $attached = array(
-      '#attached' => array(
-        'css' => array(
-          drupal_get_path('module', 'system') . '/css/system.maintenance.css' => array(),
-        ),
-        'js' => array(
-          drupal_get_path('module', 'user') . '/user.permissions.js' => array(),
-        ),
-      ),
-    );
-    drupal_render($attached);
-    drupal_process_attached($attached);
-    $view->destroy();
-
-    $output = $view->preview();
-    drupal_render($output);
-    $this->assertTrue(empty($output['#attached']['css']), 'The view does not have attached CSS.');
-    $this->assertTrue(empty($output['#attached']['js']), 'The view does not have attached JS.');
-    $view->destroy();
-
-    $output = $view->preview();
-    drupal_render($output);
-    $this->assertTrue(empty($output['#attached']['css']), 'The cached view does not have attached CSS.');
-    $this->assertTrue(empty($output['#attached']['js']), 'The cached view does not have attached JS.');
   }
 
   /**

core/modules/views/tests/modules/views_test_data/views_test_data.libraries.yml

+test:
+  css:
+    component:
+      views_cache.test.css: {}
+  js:
+    views_cache.test.js: {}

core/modules/views/tests/modules/views_test_data/views_test_data.views_execution.inc

@@ -48,13 +48,24 @@ function views_test_data_views_pre_render(ViewExecutable $view) {
 
   if (isset($view) && ($view->storage->id() == 'test_cache_header_storage')) {
     $path = drupal_get_path('module', 'views_test_data');
+    $view->element['#attached']['library'][] = 'views_test_data/test';
     $view->element['#attached']['js'][] = "$path/views_cache.test.js";
     $view->element['#attached']['css'][] = "$path/views_cache.test.css";
+    $view->element['#cache']['tags'][] = 'views_test_data:1';
+    $view->element['#post_render_cache']['views_test_data_post_render_cache'][] = ['foo' => 'bar'];
     $view->build_info['pre_render_called'] = TRUE;
   }
 
 }
 
+/**
+ * #post_render_cache callback; for testing purposes only.
+ */
+function views_test_data_post_render_cache(array $element, array $context) {
+  // No-op.
+  return $element;
+}
+
 /**
  * Implements hook_views_post_render().
  */