i wrote some code in codeigniter

index controller using model 'navigation':

$this->load->model('navigation');
$data['template']=$this->navigation->nav_template();

the nav_template() function generate string that will be output in brower:

    function nav_template($uplevel=0)
    {
        $tablename=$this->db->dbprefix("test");
        $sql="select * from $tablename where id_parent=$uplevel "
        $menu_item=$this->db->query($sql);

        foreach($menu_item->result_array() as $row)
        {
            if($something)
            {
                if
                {
                    echo 'some str';
                }
                self::nav_template($uplevel);//call self
            }
            else
            {
                echo 'other str';
            }
        }
        echo '</ul>';

    }

in view file i am using an <?php echo $template ?>
but as we all known , i am using echo() to output string. i wanted to store the string in some php varialbe that can be used in view file template tag.

and the nav_template() function just called itself using self php keyword. nowhere to define the var like this: $template=''; and no where to return the string? so , can anyone tell me how to return the output string within the nav_template() instead of echo it directly to browser?

ps: the output data is the formatted html code that will generate a treeview with help of some javascript scripts.

Originally asked by: tunpishuang on Stack Overflow