This is my first independent RoR project after working with recipes from some cool books that I've been reading...
Background: I'm building an app that could potentially useful to college students. The idea is that between semesters, students at a given campus would list textbooks that they have and textbooks that they need and the app would match them up (if I have what you want and you have what I need, its a match).
So, here are the models I've defined so far: Book, User, WantedOffer and NeedOffer. A book that is offered will have an additional attribute, such as, "condition" (new, used, like new, etc).
Class User < ActiveRecord::Base has_many wanted_offers has_many have_offers has_many books :through => wanted_offers, :have_offers end
Class Book < ActiveRecord::Base has_many wanted_offers has_many have_offers has_many users :through => wanted_offers, :have_offers end
Class HaveOffer < ActiveRecord::Base belongs_to :book belongs_to :user end
Class WantedOffer < ActiveRecord::Base belongs_to :book belongs_to :user end
I don't know if ":through => wanted_offers, :have_offers" is a valid
call (I'm looking into it) but at least now, it makes the model
relationships work in my mind 
I can get to users from books via
have_offers and wanted_offers and visa versa.
It also looks like I need a :dependent => :destroy calls somewhere since WantedOffer and HaveOffer don't make sense without a Book. I'm not sure where to put this just yet...
Thanks in advance for the help...