class User < ActiveRecord::Base
has_many :properties, :through => :actorships
has_many :actorships
end
class Property < ActiveRecord::Base
has_many :users, :through => :actorships
has_many :actorships
end
class Actorship < ActiveRecord::Base
belongs_to :user
belongs_to :property
end
user = User.last
new_actorship = user.actorships.create(:property=>Property.last, :role => 'omg')
# => Actorship associated to User and Property, with role 'omg'
user.properties
# => [Property.last]