gistfile1.rb

require 'rubygems'
require 'dm-core'
require 'dm-timestamps'

require 'pp'

DataMapper.setup(:default,
  :adapter => 'mysql',
  :host => 'localhost', 
  :username => 'root',
  :database => 'dm_core_test',
  :encoding => 'utf8'
)
 
DataMapper::Logger.new(STDOUT, :debug)
DataObjects::Mysql.logger = DataObjects::Logger.new(STDOUT, :debug)


class User
  include DataMapper::Resource

  property :id,     Serial
  property :name,  String

  has n, :friendships
  has n, :friends, :through => :friendships, :model => 'User'
end


class Friendship
  include DataMapper::Resource
 
    property :id, Serial
   belongs_to :user
   belongs_to :friend, :model => 'User'
   
end


DataMapper.auto_migrate!


users = []
users << jan = User.create(:name => 'Jan')
users << piet = User.create(:name => 'Piet')
users << klaas = User.create(:name => 'Klaas')

users.each{|u| u.save}

Friendship.new(:user => jan, :friend => piet).save
Friendship.new(:user => jan, :friend => klaas).save

pp piet.friendships

pp jan.friends