扩展模型类

Question

I'm creating a authentication engine. It has a built in model User, which contains some basic information. I want to make it possible to extend it from outside the engine (from parent app). For example to add some has_many relations. I almost managed to do this by creating:

#host_app/app/models/my_user.rb
calss MyUser < User
   has_many :comments

I thought it was it, but another problem turned out. In my engine in users show action's view I generate an additional partial which is supposed to be in host_app/app/views/shared/_partial_to_add.html.erb I also pass there the @user. This should enable me to add some additional information about the user (like the list of comment's he wrote or whatever) without touching the engine itself. But it it turns out (which is quite obvious) that this @user is almost useless because it doesn't have any new methods from the MyUser class.

Any ideas how to fix this?

Answer 1

Ruby has open classes. If you want to extend your engine's User model, you should be able to do this from the parent app:

User.class_eval do
  has_many :comments
end

(This uses class_eval so that Rails will autoload the file defining User before evaluating this code.) Put that in a file which will load when the application does; either put it in config/initializers/, or put it lib/ and require it.