Generate slug url in php codeigniter

Save this class file library generateslug.php

class GenerateSlug{
    /*
     * Developed by Manikanta
     */
    public function get_result($colName, $tbName, $cond="",$return_column_value=0){
        $ci = &get_instance();
        $ci->db->select($colName);
        if($cond!="")$ci->db->where($cond);
        $data=$ci->db->get($tbName);
        $res=$data->result();
        $ci->db->last_query();
        if($data->num_rows()>0){
            if($return_column_value==1){
                return $res[0]->option_value;
            }
        }
        return $data->num_rows()>0 ? $res : FALSE;
    }

    function generate_slug($colname, $tablename, $value){
        $newString = strtolower(preg_replace('/[^a-z0-9]/i', '_', $value));
        if($this->get_result($colname,$tablename, array($colname=>$newString))==FALSE) return $newString;
        return $this->generate_slug($colname, $tablename, $newString.rand(0,200));
    }
}

//Calling the class in controller

$crud = new GenerateSlug();
$post_array['slug']=$crud->generate_slug('slug','food_items',$post_array['name']);
print_r($post_array);