DataMapper ORM v1.8.0

[eluser]rei[/eluser]
Hi, How can i use datamapper orm and preserve the MVC logic in codeigniter. for example:

I want to get all the users, then get the posts related to each user, then get the comments for each posts of the user.

then pass the final result to the view.

Can someone please guide me how will I do that using MVC?