I have an array of product ids now i want to get all categories where these products belongs in magento2.

For example

we have categories cat_1, cat_2 ,cat_3, cat_4, cat_5, cat_6, cat_7

product_id_1 exist in cat_1, cat_2

product_id_2 exist in cat_3, cat_4

product_id_3 exist in cat_1, cat_5

Now i want a collection of category having categories cat1, cat_2, cat_3, and cat_5

4 Answers 4


You can use array_merge to get all the ids from collection

foreach($prodIds as $pid){          
    $product = $this->_productloader->create()->load($pid);   
    $proCats = $product->getCategoryIds();    
    $catIds= array_merge($catIds, $pproCats);   
$finalCat = array_unique($catIds);

If you want to get all category ids based on the array of your product ids. You can get it as following way

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$productIdsArray = array(1,2,3,4,5,6,7,8,9); // your product ids
$products = $objectManager->create("Magento\Catalog\Model\Product")->getCollection()->addAttributeToFilter('entity_id',array('in'=> $productIdsArray));

$allCategories = array();  // create a blank array
foreach ($products as $product) {
    $allCategories = array_merge($allCategories, $product->getCategoryIds());  // Merge product category ids array with $allCategories
$finalArray = array_unique($allCategories); // removes duplicate entries from an array

Note: Do not use ObjectManger directly in your phtml file. I recommend to use dependency injection.


You can always get the assigned categories of a product using following code.

In Constructor:

public function __construct(
        \Magento\Catalog\Model\ProductFactory $productFactory
    ) {
        $this->_productFactory = $productFactory;

And in your method use following code

$product = $this->_productFactory->create()->load($pid); // $pid = Product_ID

$cats = $product->getCategoryIds(); // All Categories of $product you will get in array format eg. array(catid 1, catid 2, catid 3)
  • thanks, but i want to get category collection from multiple product ids
    – Waqar
    Commented Oct 6, 2017 at 7:47
  • You can make looping of products and make an category array for all products! Hope it helps you Commented Oct 6, 2017 at 9:15

You can get collection of category by Id in block like this:

namespace Your\Modules\Block;

protected $_categoryFactory;

public function __construct(
\Magento\Catalog\Model\CategoryFactory $categoryFactory,
$this->_categoryFactory = $categoryFactory;
public function getCategory($categoryId)
    $category = $this->_categoryFactory->create();
    return $category;
public function getProductbyCategory($categoryId) 
    $products = $this->getCategory($categoryId)->getProductCollection();
    return $products;

Call function in your phtml file:

$collection = $block->getProductbyCategory($catId);
foreach($collection as $data){

Or you can define same like that in your helper and then call in phtml:

$yourHelper = $this->helper('Your\Module\Helper\Data');
$collection = $yourHelper->getProductbyCategory($catId);
foreach($collection as $data){

Hope this help.

  • Thanks, I have an array of product ids and want to get there categories
    – Waqar
    Commented Oct 6, 2017 at 8:00
  • your can try this: $product = $this->_productFactory->create()->load($pid); $product = $this->_productFactory->create()->load($pid); $cats = $product->getCategoryIds(); if(count($cats) ){ $firstCategoryId = $cats[0]; $_category = $this->_categoryFactory->create()->load($firstCategoryId); return $_category->getName(); } Commented Oct 6, 2017 at 8:31

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