gistfile1.rb

#!/usr/bin/env ruby -Ku
 
# encoding: utf-8
 
require 'rubygems'
require 'dm-core'
 
DataMapper::Logger.new($stdout, :debug)
DataMapper.setup(:default, 'sqlite3::memory:') 
 
class User
  include DataMapper::Resource
 
  property :id,   Serial
  property :name, String, :length => 1..255, :required => true, :unique => true
 
  has n, :spoken_languages
  has n, :studied_languages
  has n, :languages, :through => :spoken_languages # "piggyback" over the spoken_languages relationship
end
 
 
class SpokenLanguage
  include DataMapper::Resource
 
  property :user_id,     Integer, :min => 1, :key => true
  property :language_id, Integer, :min => 1, :key => true
 
  belongs_to :user
  belongs_to :language
end

class StudiedLanguage
  include DataMapper::Resource

  property :user_id,     Integer, :min => 1, :key => true
  property :language_id, Integer, :min => 1, :key => true

  belongs_to :user
  belongs_to :language
end
 
class Language
  include DataMapper::Resource
 
  property :id,   Serial
  property :name, String, :length => 1..255, :required => true, :unique => true
 
  has n, :spoken_languages
  has n, :speakers, :through => :spoken_languages, :via => :user, :model => 'User'

  has n, :studied_languages
  has n, :learners, :through => :studied_languages, :via => :user, :model => 'User'
end
 
DataMapper.auto_migrate!
 
english = Language.create(:name => 'English')
french  = Language.create(:name => 'French')
spanish = Language.create(:name => 'Spanish')
 
User.create(:name => 'Ben', :spoken_languages => [ english, french ], :studied_languages => [ spanish ] )
User.create(:name => 'Dan', :spoken_languages => [ english ], :studied_languages => [ french ] )
 
puts '-' * 80
 
p User.all
p User.all.languages
 
p Language.all
p Language.all.speakers