Habto
=====

Has and belongs to one

This basically acts as habtm, but has two new features.

1. Singular named accessor
2. Association counter cache


Singular named accessor
=======================

We can use not only plural named accessor but also singular one.

  class User
    habto :email
  end

  User.new.emails => []   # normal habtm accessor
  User.new.email  => nil  # useful for handling singular data


Association counter cache
=========================

:count option allows use to prefetch count of target in one find method,
where the join table is used as counter cache.

  class Keyword
    habto :image
    habto :board
  end

  class Image
    habto :keyword
  end

  class Board
    habto :keyword
  end


  ### Normal operation

  Keyword.find(1)
  => #<Keyword:0xf715348c @attributes={"name"=>"cute", "id"=>"1"}>

  ### Get the count information by :count option with association names

  Keyword.find(1, :count=>:images)
  => #<Keyword:0xf707dae4 @attributes={"name"=>"cute", "image_count"=>"4", "id"=>"1", "keyword_id"=>"1"}>
  Keyword.find(1, :count=>:boards)
  => #<Keyword:0xf707a560 @attributes={"board_count"=>"2", "name"=>"cute", "id"=>"1", "keyword_id"=>"1"}>

  ### Fetch all count information by :count option with true (same as :count=>[:images, :boards])

  Keyword.find(1, :count=>true)
  => #<Keyword:0xf7084880 @attributes={"board_count"=>"2", "name"=>"cute", "image_count"=>"4", "id"=>"1", "keyword_id"=>"1"}>


Test
====

1. create a new rails project for test
2. prepare files
     ln -s vendor/plugins/habto/spec
     rm -rf app/models
     ln -s ../spec/app/models app/models
     ln -s ../spec/migrate db/migrate
3. run migrate
4. rake spec


Copyright (c) 2008 maiha@wota.jp, released under the MIT license