How to get all the Children Categories IDs of the Specific Category in Magento2

Question

I want to get all categories of the specific category for that I tried

public function categoryHide()
    {
        $data = $this->arrayData();
        $save = array();
        $objectManager = \Magento\Framework\App\ObjectManager::getInstance(); // Instance of Object Manager
        $categoryFactory = $objectManager->get('\Magento\Catalog\Model\CategoryFactory');// Instance of Category Model
        foreach($data as $test)
        {
            $category = $categoryFactory->create()->load($test);
            // $parentCategories = $category->getParentCategories();
            $childrenCategories = $category->getChildrenCategories();
            foreach ($childrenCategories as $cat){
                $save[] = $cat->getId();
              }
        }
        return array_merge($data,$save);   
    }

}

This code is working perfectly for the Gear but if we tried to get the Ids of the Women or men category it will return only 2 children

it will only return the ids of tops and bottoms not there further children eg for women its category is 20 and tops category is 21 and bottoms category is 22 its only return there values not further children of tops and bottom. now I want to get all the child categories ids. Thanks in advance

Answer 1

you will have to solve this with recursion.

$category->getChildrenCategories() will only return direct children

public function categoryHide()
    {
        $data = $this->arrayData();
        $save = array();
        $objectManager = \Magento\Framework\App\ObjectManager::getInstance(); // Instance of Object Manager
        $categoryFactory = $objectManager->get('\Magento\Catalog\Model\CategoryFactory');// Instance of Category Model
        foreach($data as $test)
        {
            $category = $categoryFactory->create()->load($test);
            addToSave($category, $save);
        }
        return array_merge($data,$save);   
    }

}

public function addToSave($category, &$save)
{
    $childrenCategories = $category->getChildrenCategories();
    foreach ($childrenCategories as $cat){
        $save[] = $cat->getId();
        addToSave($cat, $save);
    }
} 

Answer 2

$category = $categoryFactory->create()->load($id);
$category->getAllChildren(false) - will return comma separated list of ids

Answer 3

You can try the following code :

<?php 
 $objectManager = \Magento\Framework\App\ObjectManager::getInstance(); // Instance of Object Manager
 $categoryFactory = $objectManager->get('\Magento\Catalog\Model\CategoryFactory');// Instance of Category Model
 $categoryId = 15; // YOUR CATEGORY ID
 $category = $categoryFactory->create()->load($categoryId);
 // Children  Categories
 $childrenCategories = $category->getChildrenCategories();

?>

Get all level subcategories :

<?php

function categoryLoop($id){
    $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
    $categories = $objectManager->create('Magento\Catalog\Model\Category')->load($id);

    if($categories->hasChildren()){
    echo "<ul>";
        $subcategories = explode(',', $categories->getChildren());
        foreach ($subcategories as $category) {
            $subcategory = $objectManager->create('Magento\Catalog\Model\Category')->load($category);
            echo "<li>";
            echo $subcategory->getName();
            echo "</li>";
            //echo "<br>";
            if($subcategory->hasChildren()){ categoryLoop($category); }
        }
    echo "</ul>";
    }
}

categoryLoop(2);  // enter your category id here