Add category description to “catalog/category_tree” collection

Question

class Ab_CategoryObserver_Model_Observer
{
    public function updateTopMenuJson(Varien_Event_Observer $observer)
    {
        $_helper = Mage::helper('catalog/category');
        $_categories = $_helper->getStoreCategories();
        $recursionLevel = 3; // Add recursion level
        $storeId = 1; // Add your Store ID for which you want to get category tree
        $node = '';
        $categoryTreeData = $this->getCategoryTree($recursionLevel, $storeId);
        $arr = json_encode($this->getCategoryTree(3));
        echo "<pre>";print_r($arr);
        echo("<script>console.log('PHP: ".$arr."');</script>");
        file_put_contents("cat_node.json", $arr);
    }

    protected function getCategoryTree($recursionLevel, $storeId = 1)
    {
        $parent = Mage::app()->getStore($storeId)->getRootCategoryId();
        $tree = Mage::getResourceModel('catalog/category_tree');
        /* @var $tree Mage_Catalog_Model_Resource_Category_Tree */

        $nodes = $tree->loadNode($parent)
            ->loadChildren($recursionLevel)
            ->getChildren();
        $tree->addCollectionData(null, false, $parent);

        $categoryTreeData = array();
        foreach ($nodes as $node) {
            if ($node->getIsActive()) {
                $categoryTreeData[$node->getData('entity_id')] = $this->getNodeChildrenData($node);
            }
        }

        return $categoryTreeData;
    }

    protected function getNodeChildrenData(Varien_Data_Tree_Node $node)
    {
        $categoryData = array(
            'title'       => $node->getData('name'),
            'url'         => $node->getData('url_key'),
            'id'          => $node->getId(),
            'description' => $node->getData('description'),
            'mega_menu'   => 'false'
        );

        foreach ($node->getChildren() as $childNode) {
            if (!array_key_exists('children', $categoryData)) {
                $categoryData['mega_menu'] = 'true';
                $categoryData['children']  = array();
            }
                $categoryData['children'][$childNode->getData('entity_id')] = $this->getNodeChildrenData($childNode);
        }
        return $categoryData;
    }
}

Answer 1

Category description isn't part of your collection, in getCategoryTree() change this:

$tree->addCollectionData(null, false, $parent);

To:

$collection = $tree->getCollection()
    ->addAttributeToSelect('description');
$tree->addCollectionData($collection, false, $parent);