InheritableAttributes
=====================

Useful if model attributes are to be inherited from a parent object if blank.

Example
=======

class Company < ActiveRecord::Base
  # company has an attribute "address"
  has_many :divisions
end

class Division < ActiveRecord::Base
  # division has an attribute "address"
  belongs_to :company
  
  inherit_attribute :address, :from => :company
end

class Department < ActiveRecord::Base
  # department has an attribute "address"
  belongs_to :division
  
  inherit_attribute :address, :from => :division
end


d = Department.first

d.address  #=> returns d.address, unless that value is blank, in which case
               it returns d.division.address, unless that value is blank,
               in which case it returns d.division.company.address


You can also specify more than one attribute to inherit:

class Department
  # department has an attribute "address"
  belongs_to :division
  
  inherit_attributes [:address, :telephone], :from => :division
end

If the attribute has a different name in the parent, you can use the :as
option to specify it:

class Depot < ActiveRecord::Base
  belongs_to :company
  
  inherit_attribute :postal_address, :from => :company, :as => :address
end

d = Depot.first
d.postal_address #=> returns d.postal_address, unless that value is blank,
                     in which case it returns d.company.address


Copyright (c) 2008 Jon Evans, Springy Web (UK) Ltd. Released under the MIT license

jon@springyweb.com