public function BookNavigationCacheContext::getCacheableMetadata in Drupal 8

Same name and namespace in other branches

1. 9 core/modules/book/src/Cache/BookNavigationCacheContext.php \Drupal\book\Cache\BookNavigationCacheContext::getCacheableMetadata()
2. 10 core/modules/book/src/Cache/BookNavigationCacheContext.php \Drupal\book\Cache\BookNavigationCacheContext::getCacheableMetadata()

Gets the cacheability metadata for the context.

There are three valid cases for the returned CacheableMetadata object:

• An empty object means this can be optimized away safely.
• A max-age of 0 means that this context can never be optimized away. It will never bubble up and cache tags will not be used.
• Any non-zero max-age and cache tags will bubble up into the cache item if this is optimized away to allow for invalidation if the context value changes.

Return value

\Drupal\Core\Cache\CacheableMetadata A cacheable metadata object.

Overrides CacheContextInterface::getCacheableMetadata

File

core/modules/book/src/Cache/BookNavigationCacheContext.php, line 75

Class

BookNavigationCacheContext

Defines the book navigation cache context service.

Namespace

Drupal\book\Cache

Code

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;
}