Adding Variables to AR Object

How can I add a variable to a set of objects 开发者_如何学Creturned by ActiveRecord? I've looked around and none of the methods I've seen seem to work.

Thanks in advance!

The question is vague and can be interpreted in a couple of ways.

1. Adding a variable to a list.

   list_of_objects_returned_by_activeRecord << variable
   

   This seems too simple and is probably not what you're looking for.

2. Adding a variable to each item in the list.

   Assuming your talking about instances of models, the simplest way is to add an attr_accessor to your model.

   class Model < ActiveRecord::Base
     ...
     attr_accessor :new_attribute
   end
   

   You probably want to set it to some value whenever the model is loaded so you want to add an after_initialize method to the model.For example, the following will add a nick_name attribute for every user loaded and default it to their first_name suffixed with "-O".

   class User < ActiveRecord::Base
     ...
     attr_accessor :nick_name
     def after_initialize
       self.nick_name = first_name + "-O"
     end
   end
   
   @user = User.first
   @user.first_name # => "Steve"
   @user.nick_name # => "Steve-O"
   @user.nick_name = "Tiny" # sets nick_name to "Tiny".
   @user.first_name # => Still "Steve"