From Komunitasweb.com today there's new tutorial showing how to use the DataMapper library for the CodeIgniter framework to introduce object relational mapping (ORM) to your application.
If you familiar with CodeIgniter, then you have realized by now that you can't have relationship manager. Yes, CodeIgniter doesn't have built-in ORM. But there are several projects such as IgnitedRecord and DataMapper that will help you manage relationship between your models.
The post walks you through the installation of the tool, creating some sample data to work with and creating a full model, controller and view as an example.