Simplest way to store two has_many relationships with one model in Rails?

Question

A 'user has many posts and a product has many posts, and any given post can belong to either a user or a product but not both.

I think a has_many :through relationship stored in a posts_relationships table and written like:

Class User < ActiveRecord::Base
has_many :posts, :through => posts_relationships

and

Class Product < ActiveRecord::Base
has_many :posts, :through => posts_relationships

would express what I need. Is that the correct and simplest way to do it? It's not a complex relationship so I want to write it as simply as possible.

Answer 1

consider polymorphic association.

Class User < ActiveRecord::Base
  has_many :posts, :as=>:postings
end

Class Product < ActiveRecord::Base
  has_many :posts, :as=>:postings
end

class Post
  belongs_to :posting, :polymorphic=> :true
end