Associating a resource with multiple resources?

Hi,

I have these models in my ror application: author, article and book. I
want to associate author to article and book so:

book has many authors
article has many authors
author belongs to both of them

What's the best practice for doing so? Should I have both book_id and
article_id in author table? Other solutions?

Thanks in advance,

If you have reasons to stick with the current model, then introduce a
fourth concept, call it 'Publishing'. A 'publishing' is something
that an author has written. In this case, it associates an author to
a book or an article. Now you can use two techniques --
has_many :through (as suggested by Arshak) and polymorphic
associations.

create_table :publishing do |t|
  t.reference :publishable, :polymorphic=>true
  t.reference :author
end

class Publishing < ARec::Base
  belongs_to :author
  belongs_to :publishable, :polymorphic=>true
  ...
end

class Author < ARec::Base
  has_many :publishings
  ...
end

class Book < ARec::Base
  has_many :publishings, :as=>:publishable
  has_many :authors, :through=>:publishing
  ...
end

class Article < ARec::Base
  has_many :publishings, :as=>:publishable
  has_many :authors, :through=>:publishing
  ...
end

The other possibility would be to use Single Table Inheritance,
putting the books and articles into a single table that uses a
discriminator column so that you can tell them apart. You can still
use the has_many :through concept (to support 1 or more authors) but
you eliminate one table.