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.