gistfile1.php

<?php

class Model_Category extends Model_Abstract {
    protected static $_path;
    public static function initialize(Jelly_Meta $meta)
    {
        $meta->table('categories')
            ->name_key('title')
            ->sorting(array('materialized_path' => 'asc'))
            ->fields(array(
                'id' => new Field_Primary,
                'title' => new Field_String(array(
                    'rules' => array(
                        'not_empty' => array(TRUE),
                    ),
                )),
                'level' => new Field_Integer(array(
                    'rules' => array(
                        'not_empty' => array(TRUE),
                    ),
                )),
                'materialized_path' => new Field_String(array(
                    'unique' => TRUE,
                    'rules' => array(
                        'not_empty' => array(TRUE),
                    ),
                )),
                'parent' => new Field_BelongsTo(array(
                    'foreign' => 'category.id',
                    'column' => 'parent_id',
                )),
                'children' => new Field_HasMany(array(
                    'foreign' => 'category.parent_id',
                )),
                'questions' => new Field_HasMany(array(
                    'foreign' => 'question',
                )),
                'created_at' => new Field_Timestamp(array(
                    'auto_now_create' => TRUE,
                    'format' => 'Y-m-d H:i:s',
                )),
                'updated_at' => new Field_Timestamp(array(
                    'auto_now_update' => TRUE,
                    'format' => 'Y-m-d H:i:s',
                )),
            ));
    }

    public function save($key = NULL)
    {
        // getting the level of the category
        if (empty($this->parent) == FALSE) {
            $this->level = $this->parent->level + 1;
        } else {
            $this->level = 0;
        }
        
        // setting new materialized path
        $this->set_materialized_path($this->get_materialized_path_array());

        parent::save($key);

        // flushing cache
        $this->_cache->delete('admin.cat.tree');
        $this->_cache->delete('cat.tree');
    }
    
    /**
     * Retrieves array of titles of parent categories
     */
    public function get_materialized_path_array(array $path = array())
    {
        $path[] = urlencode($this->title);

        if ($this->parent->id != NULL) {
            $path = $this->parent->get_materialized_path_array($path);
        }

        return $path;

    }

    protected function set_materialized_path(array $array)
    {
        // the argument is a reverse array
        $this->materialized_path = implode('/', array_reverse($array));
    }

    /*
     * Categories from root to current
     *
     * @return  array
     */
    public function get_path()
    {

        $category = $this;
        // creating categories path array
        $categories = array($this);
        // while we reach the root category
        while ($category->parent->id != NULL) {
            // we add category parent to array
            $category = $category->parent;
            $categories[] = $category;
        }
        // reverting the array so that root category went first
        return array_reverse($categories);
    }

    /*
     * Delete the category and all the other stuff that concerns it.
     *
     * @param   int     category id to delete
     */
    public function delete($key = NULL)
    {
        // subcategories
        Jelly::delete('category')->subs($this)->execute();
        // and this
        parent::delete($key);
        // flushing the cache
        $this->_cache->delete_all();
    }
}