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 © 2008 [email protected], released under the MIT license