gistfile1.txt

#!/usr/bin/env ruby
 
require 'dm-core'
 
class Foo
  include DataMapper::Resource
  property :id, Serial
 
  has n, :bars
end
 
class Bar
  include DataMapper::Resource
  property :id, Serial
 
  # Does not belong to foo.
  #belongs_to :foo, :nullable => true
end
 
DataMapper.setup(:default, 'sqlite3::memory:')
DataMapper.auto_migrate!

# Bar#foo and Bar#foo= will get called if they're added after DataMapper.setup
class Bar
  def foo
    puts 'I never get called.'
  end
  
  def foo=(other)
    puts 'neither do i'
  end
end
 
foo = Foo.create
foo.bars.create
bar = foo.bars.first
 
bar.foo = 'boom'
 
bar.foo # also boom