/**
* Add list of associated identities to the top menu block for caching purposes.
*
* @param \Magento\Theme\Block\Html\Topmenu $subject
* @return void
*/
public function beforeGetIdentities(\Magento\Theme\Block\Html\Topmenu $subject)
{
$subject->addIdentity(Category::CACHE_TAG);
$rootId = $this->storeManager->getStore()->getRootCategoryId();
$storeId = $this->storeManager->getStore()->getId();
/** @var \Magento\Catalog\Model\ResourceModel\Category\Collection $collection */
$collection = $this->getCategoryTree($storeId, $rootId);
$mapping = [$rootId => $subject->getMenu()];
// use nodes stack to avoid recursion
foreach ($collection as $category) {
if (!isset($mapping[$category->getParentId()])) {
continue;
}
$subject->addIdentity(Category::CACHE_TAG . '_' . $category->getId());
}
}
