Problem
MenuLinkTree::buildItems ignores cacheable metadata of disabled links. This is bad for dynamically enabled links.
Example
I have created a simple menu link plugin which shows a link to the front page on any page except the front page itself. Code:
<?php
namespace Drupal\blablabla\Plugin\Menu;
use Drupal\Core\Menu\MenuLinkDefault;
use Drupal\Core\Menu\StaticMenuLinkOverridesInterface;
use Drupal\Core\Path\PathMatcherInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
/**
* A menu link for front page.
*/
class FrontpageMenuLink extends MenuLinkDefault {
/**
* The path matcher.
*
* @var \Drupal\Core\Path\PathMatcherInterface
*/
protected $pathMatcher;
/**
* Constructs a new FrontpageMenuLink.
*
* @param array $configuration
* A configuration array containing information about the plugin instance.
* @param string $plugin_id
* The plugin_id for the plugin instance.
* @param mixed $plugin_definition
* The plugin implementation definition.
* @param \Drupal\Core\Menu\StaticMenuLinkOverridesInterface $static_override
* The static override storage.
* @param \Drupal\Core\Path\PathMatcherInterface $path_matcher
* The path matcher.
*/
public function __construct(array $configuration, $plugin_id, $plugin_definition, StaticMenuLinkOverridesInterface $static_override, PathMatcherInterface $path_matcher) {
parent::__construct($configuration, $plugin_id, $plugin_definition, $static_override);
$this->pathMatcher = $path_matcher;
}
/**
* {@inheritdoc}
*/
public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
return new static(
$configuration,
$plugin_id,
$plugin_definition,
$container->get('menu_link.static.overrides'),
$container->get('path.matcher')
);
}
/**
* {@inheritdoc}
*/
public function getTitle() {
return $this->t('Frontpage');
}
/**
* {@inheritdoc}
*/
public function getRouteName() {
return '<front>';
}
/**
* {@inheritdoc}
*/
public function getCacheContexts() {
return ['url.path.is_front'];
}
/**
* {@inheritdoc}
*/
public function isEnabled()
{
return (parent::isEnabled() && !$this->pathMatcher->isFrontPage());
}
}
?>
Steps to reproduce cache ignorance:
- Use this plugin, place a link of it into the main menu
- Clear cache
- Request the front page: No link to front page is set (OK)
- Request a page other than front: No link to front page is set (not OK, because wrong cache record is being fetched).
- Clear cache
- Request a page other than front: You see the link to front page (OK, because Drupal now knows about the cache context)
- Request the front page: No link to front page is set (OK)
Proposed solution
Collect cache metadata from links regardless whether they're disabled or not. I'm attaching a patch for this.