QueryArgsCacheContext.php

<?php

namespace Drupal\Core\Cache\Context;

use Drupal\Core\Cache\CacheableMetadata;

/**
 * Defines the QueryArgsCacheContext service, for "per query args" caching.
 *
 * Cache context ID: 'url.query_args' (to vary by all query arguments).
 * Calculated cache context ID: 'url.query_args:%key', e.g.'url.query_args:foo'
 * (to vary by the 'foo' query argument).
 */
class QueryArgsCacheContext extends RequestStackCacheContextBase implements CalculatedCacheContextInterface {
    
    /**
     * {@inheritdoc}
     */
    public static function getLabel() {
        return t('Query arguments');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext($query_arg = NULL) {
        if ($query_arg === NULL) {
            // All arguments requested. Use normalized query string to minimize
            // variations.
            $value = $this->requestStack
                ->getCurrentRequest()
                ->getQueryString();
            return $value !== NULL ? $value : '';
        }
        elseif ($this->requestStack
            ->getCurrentRequest()->query
            ->has($query_arg)) {
            $value = $this->requestStack
                ->getCurrentRequest()->query
                ->get($query_arg);
            if (is_array($value)) {
                return http_build_query($value);
            }
            elseif ($value !== '') {
                return $value;
            }
            return '?valueless?';
        }
        return '';
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata($query_arg = NULL) {
        return new CacheableMetadata();
    }

}