gistfile1.rb

require 'datamapper'

class Person
  include DataMapper::Resource

  property :id, Serial
  property :name, String

  has n, :managers, 'Person', :through => Resource
  has n, :managees, 'Person', :through => :managers, :child_key => [:person_id]

end

DataMapper.setup :default, 'sqlite3::memory:'
DataMapper.auto_migrate!

user1 = Person.create(:name => 'Dan Kubb')
user2 = Person.create(:name => 'John Doe', :managers => [ user1 ])



user1.save!
user2.save!