如何在magento中过滤目录/类别

Question

我正在尝试获取仅限于搜索查询的类别列表 $ searchstring 这是我必须过滤产品

$_productCollection = Mage::getModel('catalog/product')
                    ->getCollection()
                    ->addAttributeToSort('created_at', 'DESC')
                    ->addAttributeToSelect('*')
                    ->setPageSize(20)
                    ->addAttributeToFilter('name', array('like' => '%'.$searchstring.'%'))<---this line
                    ->load();

但是我需要过滤类别。如何编辑以下代码来过滤类似上面的类别

$_helper = Mage::helper('catalog/category');
$_categories = $_helper->getStoreCategories();
if (count($_categories) > 0){
    foreach($_categories as $_category){
        $_category = Mage::getModel('catalog/category')->load($_category->getId());
        $_subcategories = $_category->getChildrenCategories();
        if($_category->getImageUrl()!= ""){$categoryimage = $_category->getImageUrl();}else{$categoryimage = "http://www.flintout.com/img/roughrock.jpg";}

                 echo $categoryimage;
                 echo $_category->getName();
                 echo $_category->getDescription();

        if (count($_subcategories) > 0){                
            foreach($_subcategories as $_subcategory){
                if($_subcategory->getImageUrl()!= ""){$subcategoryimage = $_subcategory->getImageUrl();}else{$subcategoryimage = "http://www.flintout.com/img/roughrock.jpg";}

                 echo $subcategoryimage;
                 echo $_subcategory->getName();
                 echo $_subcategory->getDescription();

            }
        }
    }
}

谢谢