MPTtree, Hieararchical trees in a database table

[eluser]crises[/eluser]
I finally found a way of doing a collapsible tree menu from data stored in this way (in my case categories of products for an online catalog). But now i would like to know if this solution is efficient.

In my app i have categories stored as:

Code:

+Root
|--Main Category 1
| |--Subcat 1
| |--Subcat 2
| | |--Sub-subcat 1
| | |--Sub-subcat 2
| |--Subcat 3
|--Main Category 2
| |--Subcat 4
| |--Subcat 5
|   |--Sub-subcat 3
|--Main Category 3
|--Main Category 4
| |--Subcat 6
| |--Subcat 7

I think you got the idea, nothing strange Then i want a menu that firstly shows only the Main Categories, and then if i click in Main Category 1 for example it shows ONLY the first two childs of Main Category (Subcat 1 and Subcat 2). Then if i click in Subcat 2 the menu should show me the childs of Main Category 1 plus childs of Subcat 2. And so on, usual menu as shown in many websites.

To the point. In my catalog controller:

Code:

function category($current_category_url = null, $page=null)
{
    /*Rest of stuf*/

    $current_category = $this->Catalog_model->get_current_category($current_category_url);//Array with all data of the current category
    $root = $this->MPTtree->get_root();
    $main_categories = $this->MPTtree->get_children($root['lft'], $root['rgt']);//only Main Categories, without their childrens
    $data['menu'] = $this->Catalog_model->do_menu($main_categories, $current_category);

    /*Rest of stuf*/
}

And the functions in the model (Catalog_model):

Code:

function get_current_category($category_url)
{
    $this->db->select('*');
    $this->db->from('prod_category');
    $this->db->where('category_url =', $category_url);
    $this->db->limit(1);
    $query = $this->db->get();
    
    if ($query->num_rows() > 0)
    {
        $result = $query->row_array();
        return $result;
    }
}

function do_menu($tree, $current_category)
{
    $category_childrens = $this->MPTtree->get_children($current_category['lft'], $current_category['rgt']);
    $parents_current_category = $this->MPTtree->get_parents($current_category['lft'], $current_category['rgt']);
    $str = '<ul class="category-list>"';
    foreach($tree as $category)
    {
        $str .= '<li>';
        if ($category['name'] == $current_category['name'])
        {
            $str .= '<strong><a href="'.base_url().'catalog/category/'.$category['category_url'].'">'.$category['name'].'</a></strong>';
            $str .= $this->do_submenu($category_childrens, $current_category);
        }
        else
        {
            $str .= '<a href="'.base_url().'catalog/category/'.$category['category_url'].'">'.$category['name'].'</a>';
        }
        if ($current_parent = $this->check_parents($category, array_reverse($parents_current_category)))
        {
            $childrens_of_current_parent = $this->MPTtree->get_children($current_parent['lft'], $current_parent['rgt']);
            $str .= $this->do_submenu($childrens_of_current_parent, $current_category);
        }
        $str .= '</li>';
    }
    $str .= '</ul>';
    return $str;
}

function do_submenu($tree, $current_category)
{
    $category_childrens = $this->MPTtree->get_children($current_category['lft'], $current_category['rgt']);
    $parents_current_category = $this->MPTtree->get_parents($current_category['lft'], $current_category['rgt']);
    $str = '<ul class="subcategory-list">';
    foreach($tree as $category)
    {
        $str .= '<li>';
        if ($category['name'] == $current_category['category'])
        {
            $str .= '<strong><a href="'.base_url().'catalog/category/'.$category['category_url'].'">'.$category['name'].'</a></strong>';
            $str .= $this->do_submenu($category_childrens, $category);
        }
        else
        {
            $str .= '<a href="'.base_url().'catalog/category/'.$category['category_url'].'">'.$category['name'].'</a>';
        }
        if ($current_parent = $this->check_parents($category, array_reverse($parents_current_category)))
        {
            $childrens_of_current_parent = $this->MPTtree->get_children($current_parent['lft'], $current_parent['rgt']);
            $str .= $this->do_submenu($childrens_of_current_parent, $current_category);
        }
        $str .= '</li>';
    }
    $str .= '</ul>';
    return $str;
}
    
function check_parents($category, $parents_current_category)
{
    foreach($parents_current_category as $parent)
    {
        if ($category['name'] == $parent['name'] && $parent['name'] != 'Root') //Name of root node in tree
        {
            $current_parent = $parent;
            return $current_parent;
            exit;
        }
    }
}

Functions do_menu() and do_submenu() are esentially the same, but as i want different <ul> class i had to make two functions. If you dont need it you can only use one function. Well the code is not as simple as i would like, but at least is working. Now the question again: it is efficient enought? ty