December 2, 2020Lokesh S

Magento 2 How to Get Categories From Specific Product

Here we will get categories from specific product. It is allowed to get the list from current or any product as you need.

Now you will need to open the block class of custom module (Magemeta_CategoryProduct), then inject the object of \Magento\Catalog\Model\ResourceModel\Category\CollectionFactory, \Magento\Catalog\Model\ProductRepository and \Magento\Framework\Registry classes in the constructor of that block class.

app/code/Magemeta/CategoryProduct/Block/CategoryProduct.php

<?php
namespace Magemeta\CategoryProduct\Block;
class CategoryProduct extends \Magento\Framework\View\Element\Template
{    
    protected $_categoryCollectionFactory;
    protected $_productRepository;
    protected $_registry;
        
    public function __construct(
        \Magento\Backend\Block\Template\Context $context,        
        \Magento\Catalog\Model\ResourceModel\Category\CollectionFactory $categoryCollectionFactory,
        \Magento\Catalog\Model\ProductRepository $productRepository,
        \Magento\Framework\Registry $registry,
        array $data = []
        )
        {
            $this->_categoryCollectionFactory = $categoryCollectionFactory;
            $this->_productRepository = $productRepository;
            $this->_registry = $registry;
            parent::__construct($context, $data);
    }
    
    /**
     * Get category collection
     *
     * @param bool $isActive
     * @param bool|int $level
     * @param bool|string $sortBy
     * @param bool|int $pageSize
     * @return \Magento\Catalog\Model\ResourceModel\Category\Collection or array
     */
    public function getCategoryCollection($isActive = true, $level = false, $sortBy = false, $pageSize = false)
    {
        $collection = $this->_categoryCollectionFactory->create();
        $collection->addAttributeToSelect('*');        
        
        // select only active categories
        if ($isActive) {
            $collection->addIsActiveFilter();
        }
                
        // select categories of certain level
        if ($level) {
            $collection->addLevelFilter($level);
        }
        
        // sort categories by some value
        if ($sortBy) {
            $collection->addOrderField($sortBy);
        }
        
        // select certain number of categories
        if ($pageSize) {
            $collection->setPageSize($pageSize); 
        }    
        
        return $collection;
    }
    
    public function getProductById($id)
    {        
        return $this->_productRepository->getById($id);
    }
    
    public function getCurrentProduct()
    {        
        return $this->_registry->registry('current_product');
    }
}
?>

In case you want to work with the current product, the getCurrentProduct() funciton is active. And if from any specific item, please enable getProductById($id) function. After that, you can retrieve the collection of the category from the category IDs which are linked to that product. In the .phtml file, you need to add the following code snippet:

$productId = 1; // YOUR PRODUCT ID
$product = $block->getProductById($productId);
 
// for current product
// $product = $block->getCurrentProduct();
 
$categoryIds = $product->getCategoryIds(); 
$categories = $block->getCategoryCollection()
                    ->addAttributeToFilter('entity_id', $categoryIds);
                    
foreach ($categories as $category) {
    echo $category->getName() . '<br>';
}

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