Magento 2. How to get All Parent Categories Ids from current category ID

Question

I'm getting the current category Id using Registry like

$categoryId = $this->_registry->registry('current_category')->getId();

and to get the parent categories I tried this

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$categoryFactory=$objectManager>get('\Magento\Catalog\Model\CategoryFactory');
$category = $categoryFactory->create()->load($categoryId);
$parentCategories = $category->getParentCategories();

Now when Print_r() this category then it shows me memory limit but I just want to show all the Ids of the parent categories I also tried

$parentCategories = $category->getParentCategories()->getId();

but it shows me an error... how can I get only the Ids of the parent categories? Thanks in advance

Answer 1

Just iterate throu the collection (assuming you have all parent categories in the collection like you posted above - I'm not sure you will get them that way),run foreach:

foreach ($parentCategories as $cat){
  echo $cat->getId();
}

But there is a nice method in the category model called getParentIds(). That should work:

$category->getParentIds();