ActsAsDefaultable

This acts_as extension provides the capability for having a default object. The class that has this specified needs to have a default column defined as an integer, string or boolean on the mapped database table. There is also optional support for each record to have a default object of another model.

In your Gemfile

  gem 'acts_as_defaultable'

Currently is tested on rails3.2, ruby 1.9.3 and mysql

  class Country < ActiveRecord::Base
    acts_as_defaultable :default
  end

  gr = Country.new
  gr.default = true
  gr.save
  Country.default == gr # => true
  uk = Country.new
  uk.default = true
  uk.save
  Country.default == gr # => false

If no options provided default column is assumed.

  class User < ActiveRecord::Base
    acts_as_defaultable :default, relation: :post
  end

  class Post < ActiveRecord::Base
    after_destroy User.new
  end

  class Comment < ActiveRecord::Base
  end

  user = User.new
  post = Post.create
  user.default_post = post
  user.save
  user.default_post == post # => true

  post.destroy
  user.reload
  user.default_post == nil # => true

  user.default_post = Comment.create
  user.default_post == nil # => true

Only an object of the relation class will be accepted. The after_destroy callback is optional but will ensure that results stay consistent in the event that a newly created post gets the same id as the one destroyed

The option to acts_as_defaultable is the column of the Model that defines default behaviour. This column can be a string, a boolean or an integer with default positive values 'on', true, 1 and default negative values 'off', false, 0 respectively.

The column name for a default relation is default_column _ relation_column and can be either a string or an integer.

Examples:

  class User < ActiveRecord::Base
    acts_as_defaultable :default, relation: :post
  end

Column name in users table must be default_post

  class User < ActiveRecord::Base
    acts_as_defaultable :unique, relation: :post
  end

Column name must be unique_post

acts_as_defaultable is released under the MIT License