Version 1

[yaffs-website] / web / core / modules / book / src / Cache / BookNavigationCacheContext.php

diff --git a/web/core/modules/book/src/Cache/BookNavigationCacheContext.php b/web/core/modules/book/src/Cache/BookNavigationCacheContext.php
new file mode 100644 (file)
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+++ b/web/core/modules/book/src/Cache/BookNavigationCacheContext.php
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+<?php
+
+namespace Drupal\book\Cache;
+
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Cache\Context\CacheContextInterface;
+use Symfony\Component\DependencyInjection\ContainerAwareInterface;
+use Symfony\Component\DependencyInjection\ContainerAwareTrait;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * Defines the book navigation cache context service.
+ *
+ * Cache context ID: 'route.book_navigation'.
+ *
+ * This allows for book navigation location-aware caching. It depends on:
+ * - whether the current route represents a book node at all
+ * - and if so, where in the book hierarchy we are
+ *
+ * This class is container-aware to avoid initializing the 'book.manager'
+ * service when it is not necessary.
+ */
+class BookNavigationCacheContext implements CacheContextInterface, ContainerAwareInterface {
+
+  use ContainerAwareTrait;
+
+  /**
+   * The request stack.
+   *
+   * @var \Symfony\Component\HttpFoundation\RequestStack
+   */
+  protected $requestStack;
+
+  /**
+   * Constructs a new BookNavigationCacheContext service.
+   *
+   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
+   *   The request stack.
+   */
+  public function __construct(RequestStack $request_stack) {
+    $this->requestStack = $request_stack;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getLabel() {
+    return t("Book navigation");
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getContext() {
+    // Find the current book's ID.
+    $current_bid = 0;
+    if ($node = $this->requestStack->getCurrentRequest()->get('node')) {
+      $current_bid = empty($node->book['bid']) ? 0 : $node->book['bid'];
+    }
+
+    // If we're not looking at a book node, then we're not navigating a book.
+    if ($current_bid === 0) {
+      return 'book.none';
+    }
+
+    // If we're looking at a book node, get the trail for that node.
+    $active_trail = $this->container->get('book.manager')
+      ->getActiveTrailIds($node->book['bid'], $node->book);
+    return implode('|', $active_trail);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata() {
+    // The book active trail depends on the node and data attached to it.
+    // That information is however not stored as part of the node.
+    $cacheable_metadata = new CacheableMetadata();
+    if ($node = $this->requestStack->getCurrentRequest()->get('node')) {
+      // If the node is part of a book then we can use the cache tag for that
+      // book. If not, then it can't be optimized away.
+      if (!empty($node->book['bid'])) {
+        $cacheable_metadata->addCacheTags(['bid:' . $node->book['bid']]);
+      }
+      else {
+        $cacheable_metadata->setCacheMaxAge(0);
+      }
+    }
+    return $cacheable_metadata;
+  }
+
+}