ActsAsInheritable

Acts As Inheritable is a Ruby Gem specifically written for Rails/ActiveRecord models. It is meant to be used with the Self-Referential Association, or with a model having a parent that shares the inheritable attributes. This will let you inherit any attribute or relation from the parent model.

This is a code example on how to implement Self-Referential Association

class Person < ActiveRecord::Base
  belongs_to :parent, class: Person
  has_many :children, class: Person, foreign_key: :parent_id
  has_many :grandchildren, class: Person, through: :children, source: :children
end

Add this line to your application's Gemfile:

gem 'acts_as_inheritable'

And then execute:

$ bundle

Or install it yourself as:

$ gem install acts_as_inheritable

You can enable ActsAsInheritable by adding acts_as_inheritable into your model. You need to define at least one option, either attributes or associations. Those options are arrays containing the atrributes names or the associations names.

class Person < ActiveRecord::Base

  acts_as_inheritable attributes: %w(favorite_color last_name soccer_team),
                      associations: %w(shoes pictures clan)

  # Associations
  belongs_to  :parent, class_name: 'Person'
  belongs_to  :clan
  has_many    :children, class_name: 'Person', foreign_key: :parent_id
  has_many    :toys
  has_many    :shoes
  has_one     :pet
  has_many    :pictures, as: :imageable

  # Callbacks
  before_validation :inherit_attributes, on: :create
  before_validation :inherit_relations, on: :create
end

parent = Person.create(last_name: 'Arango', soccer_team: 'Verdolaga', favorite_color:'Green')

son = Person.create(parent: parent)
son.last_name # => Arango
son.soccer_team # => Verdolaga
son.favorite_color # => Green

By adding acts_as_inheritable to your models you will have access to these methods:

Signature inherit_attributes(force = false, not_force_for = [], method_to_update = nil)

By default this method will only set values that are blank?.

• force: Default to true. Set the attribute even if it's present.
• not_force_for: Default to empty array. When setting force to true, you can also specify the attributes you don't want to overwrite.
• method_to_update: Default to nil. Uses the specified method (update_attributes or update_columns) instead of the normal asignation ("#{attribute}="). This is useful if you're using inherit_attributes inside an after_save callback or if you want to skip validations for example.

Signature inherit_relations(model_parent = send(:parent), current = self)

class Person < ActiveRecord::Base

  acts_as_inheritable associations: %w(pet)

  # Associations
  has_one     :pet

  # Callbacks
  before_validation :inherit_relations, on: :create
end

parent = Person.create(last_name: 'Arango')
parent_pet = Pet.create(person: parent, name: 'Mango', breed:'Golden Retriver')
parent_pet.inspect #=> #<Pet id: 1, person_id: 1, name: "Mango", breed: "Golden Retriver">

son = Person.create(parent: parent)
son.pet.inspect # => #<Pet id: 2, person_id: 2, name: "Mango", breed: "Golden Retriver">

By default new relations are duplicated using dup, which produces a shallow copy of the object. But you can also handle this as you want by defining a duplicate! method.

All tests follow the RSpec format and are located in the spec directory. They can be run with:

$ rspec

1. Fork it ( https://github.com/esbanarango/acts_as_inheritable/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Support this project and others by esbanarango via gratipay.

This was written by Esteban Arango Medina while working at Blue Sky Cards.

Thanks to @danielosorio83 who also wrote part of the logic for this gem.