親子のモデルのビューヘルパー

Rails

親子のモデルのビューヘルパー　(例：Mother -> Sister)
6人目のMotherからSisterを作るときに悩んだ。

at config/route.rb

      map.resources :mothers, :has_one => :sisters

at app/views/mothers/index.html.erb

    <%= link_to 'New mother', new_mother_path %>
    <%= link_to 'Edit', edit_mother_path(mother) %>
    <%= link_to 'Make Sister', new_mother_sisters_path(mother)  %>

at app/models/mother.rb

class Mother < ActiveRecord::Base
  has_one :sister
end

at app/models/sister.rb

class Sister < ActiveRecord::Base
  belongs_to :mother
end