Magento 2: How to get product collection by category?

Question

We are trying to get product collection by category id.

Block:

protected $_categoryFactory;

public function __construct(
    \Magento\Backend\Block\Template\Context $context,       
    \Magento\Catalog\Model\CategoryFactory $categoryFactory,
    array $data = []
)
{   
    $this->_categoryFactory = $categoryFactory;
    parent::__construct($context, $data);
}

public function getCategory($categoryId) 
{
    $category = $this->_categoryFactory->create();
    $category->load($categoryId);
    return $category;
}

public function getCategoryProducts($categoryId) 
{
    $products = $this->getCategory($categoryId)->getProductCollection();
    $products->addAttributeToSelect('*');
    return $products;
}  

and in html:

$categoryId = 6; // fetching products in category id 6
$categoryProducts = $block->getCategoryProducts($categoryId);
foreach ($categoryProducts as $product) {
    echo $product->getName() . ' - ' . $product->getProductUrl() . '<br />';
}

it works fine only if $categoryId = the highest level in the category tree. But if I change $categoryId to 2 (or 3... or etc but not last in category tree) it doesn't work.

How can I get it work?

Answer 1

I did this task in this way: In block:

protected $_objectManager = null;
protected $_categoryFactory;
protected $_category;
protected $_productCollectionFactory;

public function __construct(
    \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory,
    \Magento\Framework\View\Element\Template\Context $context,
    \Magento\Framework\ObjectManagerInterface $objectManager,
    \Magento\Catalog\Model\CategoryFactory $categoryFactory
) {
    $this->_productCollectionFactory = $productCollectionFactory;
    $this->_objectManager = $objectManager;
    $this->_categoryFactory = $categoryFactory;
    parent::__construct($context);
}


public function getCurrentCategory()
{
    $category = $this->_objectManager->get('Magento\Framework\Registry')->registry('current_category');
    return $category;
}

/**
 * Get category object
 *
 * @return \Magento\Catalog\Model\Category
 */
public function getCategory($categoryId)
{
    $this->_category = $this->_categoryFactory->create();
    $this->_category->load($categoryId);
    return $this->_category;
}

/**
 * Get all children categories IDs
 *
 * @param boolean $asArray return result as array instead of comma-separated list of IDs
 * @return array|string
 */
public function getAllChildren($asArray = false, $categoryId = false)
{
    if ($this->_category) {
        return $this->_category->getAllChildren($asArray);
    } else {
        return $this->getCategory($categoryId)->getAllChildren($asArray);
    }
}

public function getProductCollection($category_id_array)
{
    $collection = $this->_productCollectionFactory->create();
    $collection->addAttributeToSelect('*');
    $collection->addCategoriesFilter(['in' => $category_id_array]);
    $collection->addAttributeToFilter('visibility', \Magento\Catalog\Model\Product\Visibility::VISIBILITY_BOTH);
    $collection->addAttributeToFilter('status',\Magento\Catalog\Model\Product\Attribute\Source\Status::STATUS_ENABLED);
    $collection->setPageSize(9); // fetching only 9 products
    return $collection;
}

In phtml:

<?php
    $category_id_array = $this->getAllChildren(true,$this->getCurrentCategory()->getEntity_id());
    foreach ($block->getProductCollection($category_id_array) as $product) {
        var_dump($product->getData());
    }
?>

and it works in any category.

Answer 2

You can try the following code to resolve your query:

$objectManager = \Magento\Framework\App\ObjectManager::getInstance(); 
$cateinstance = $objectManager->create('Magento\Catalog\Model\CategoryFactory');
$cateid = '14';
$allcategoryproduct = $cateinstance->create()->load($cateid)->getProductCollection()->addAttributeToSelect('*');