Datamapper and pagination

[eluser]kakallatt[/eluser]
[quote author="WanWizard" date="1366871686"]Then your relationship definition is wrong, can you post it?[/quote]

I dont' know how to defined relationship for self-relation.
My problem is: I have a parent_id and I want to use it for get the name of page

I usually use:

Code:

$this->db->select('pages.*, p.slug as parent_slug, p.title as parent_title');
  $this->db->join('pages as p', 'pages.parent_id=p.id', 'left');

But in datamapper ORM, I don't know how to defined the relation correctly. Thank you