HeadersCacheContext.php

Same filename in other branches
  1. 9 core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
  2. 8.9.x core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
  3. 10 core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php

Namespace

Drupal\Core\Cache\Context

File

core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php

View source
<?php

namespace Drupal\Core\Cache\Context;

use Drupal\Core\Cache\CacheableMetadata;

/**
 * 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).
 */
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();
    }

}

Classes

Title Deprecated Summary
HeadersCacheContext Defines the HeadersCacheContext service, for "per header" caching.

Buggy or inaccurate documentation? Please file an issue. Need support? Need help programming? Connect with the Drupal community.