class BookNavigationCacheContext in Drupal 8

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.

Hierarchy

• class \Drupal\book\Cache\BookNavigationCacheContext implements \Symfony\Component\DependencyInjection\ContainerAwareInterface, CacheContextInterface uses \Symfony\Component\DependencyInjection\ContainerAwareTrait

1 string reference to 'BookNavigationCacheContext'

book.services.yml in core/modules/book/book.services.yml

core/modules/book/book.services.yml

1 service uses BookNavigationCacheContext

cache_context.route.book_navigation in core/modules/book/book.services.yml

Drupal\book\Cache\BookNavigationCacheContext

File

core/modules/book/src/Cache/BookNavigationCacheContext.php, line 23

Namespace

Drupal\book\Cache

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;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
BookNavigationCacheContext::$requestStack	protected	property	The request stack.
BookNavigationCacheContext::getCacheableMetadata	public	function	Gets the cacheability metadata for the context. Overrides CacheContextInterface::getCacheableMetadata
BookNavigationCacheContext::getContext	public	function	Returns the string representation of the cache context. Overrides CacheContextInterface::getContext
BookNavigationCacheContext::getLabel	public static	function	Returns the label of the cache context. Overrides CacheContextInterface::getLabel
BookNavigationCacheContext::__construct	public	function	Constructs a new BookNavigationCacheContext service.