class HeadersCacheContext

Defines the HeadersCacheContext service, for "per header" caching.

Cache context ID: 'headers' (to vary by all headers). Calculated cache context ID: 'headers:%name', e.g. 'headers:X-Something' (to vary by the 'X-Something' header).

Hierarchy

Expanded class hierarchy of HeadersCacheContext

1 file declares its use of HeadersCacheContext
HeadersCacheContextTest.php in core/tests/Drupal/Tests/Core/Cache/Context/HeadersCacheContextTest.php
1 string reference to 'HeadersCacheContext'
core.services.yml in core/core.services.yml
core/core.services.yml
1 service uses HeadersCacheContext
cache_context.headers in core/core.services.yml
Drupal\Core\Cache\Context\HeadersCacheContext

File

View on git.drupalcode.org

core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php, line 14

Namespace

Drupal\Core\Cache\Context
View source 
class HeadersCacheContext extends RequestStackCacheContextBase implements CalculatedCacheContextInterface {
  
  /**
   * {@inheritdoc}
   */
  public static function getLabel() {
    return t('HTTP headers');
  }
  
  /**
   * {@inheritdoc}
   */
  public function getContext($header = NULL) {
    if ($header === NULL) {
      $headers = $this->requestStack
        ->getCurrentRequest()->headers
        ->all();
      // Order headers by name to have less cache variations.
      ksort($headers);
      $result = '';
      foreach ($headers as $name => $value) {
        if ($result) {
          $result .= '&';
        }
        // Sort values to minimize cache variations.
        sort($value);
        $result .= $name . '=' . implode(',', $value);
      }
      return $result;
    }
    elseif ($this->requestStack
      ->getCurrentRequest()->headers
      ->has($header)) {
      $value = $this->requestStack
        ->getCurrentRequest()->headers
        ->get($header);
      if ($value !== '') {
        return $value;
      }
      return '?valueless?';
    }
    return '';
  }
  
  /**
   * {@inheritdoc}
   */
  public function getCacheableMetadata($header = NULL) {
    return new CacheableMetadata();
  }

}

Members

Title Modifiers Object type Summary Overriden Title
HeadersCacheContext::getCacheableMetadata public function Gets the cacheability metadata for the context based on the parameter value. Overrides CalculatedCacheContextInterface::getCacheableMetadata
HeadersCacheContext::getContext public function Returns the string representation of the cache context. Overrides CalculatedCacheContextInterface::getContext
HeadersCacheContext::getLabel public static function Returns the label of the cache context. Overrides CalculatedCacheContextInterface::getLabel
RequestStackCacheContextBase::$requestStack protected property The request stack.
RequestStackCacheContextBase::__construct public function Constructs a new RequestStackCacheContextBase class.

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