That's a clean solution, however I don't know if it satisfies the fact that "any Room might have many different combinations of Rounds"
Not sure I understand correctly, but if a room can have many combination of rounds, and each combination of rounds has more than one round, you could try this: Room and Round models I assume you already have. A room can have many round_combinations (create the RoundCombination model with a room_id. Room :has_many :room_combinations, and RoomCombination :belongs_to :room). Then create a join table between round_combinations and rounds (HABTM). You can use callbacks or validation to limit the relationship to two rounds maximum. On Feb 14, 11:42 pm, Maurício Linhares <mauricio.linha...@gmail.com> wrote: > Imagining that every round must belong to a room, here's a simple and > straightforward implementation: > > class Room < ActiveRecord::Base > # this class needs a max_rounds and rounds_count integer columns > has_many :rounds > > def accepts_more_rounds? > max_rounds < rounds_count > end > > end > > class Round < ActiveRecord::Base > # this class needs a room_id integer column > belongs_to :room, :counter_cache => true > > validate_on_create :validate_rounds_count > > protected > > def validate_rounds_count > self.room.reload > unless self.room.accepts_more_rounds? > errors.add( :room, "has already met it's rounds limit" ) > end > end > > end > > room = Room.create( :max_rounds => 2 ) > round_1 = room.rounds.create( :name => 'round 1' ) > round_2 = room.rounds.create( :name => 'round 2' ) > round_3 = room.rounds.create( :name => 'round 3' ) # this one isn't > going to be created > round_3.new_record? == true > > - > Maurício Linhareshttp://alinhavado.wordpress.com/(pt-br) > |http://blog.codevader.com/(en) > > On Sat, Feb 14, 2009 at 7:53 PM, Greg Brockman > > <gregory.brock...@gmail.com> wrote: > > > Hey all, > > > I have a pretty simple question, but I'm not sure of a good solution > > to it. Essentially, I want to provide a two-to-one mapping of models. > > I'm working on an application for a contest, where every (unordered) > > combination of two Rounds is supposed to be assigned to one Room. Any > > Room might have many different combinations of Rounds, however. > > > What is the Right Way of doing this in Rails? Maybe create a model > > that holds the associated foreign keys? Also, what would be a good > > way to scale this out, if I wanted to be able to map unordered > > n-element collections of Rounds to obtain a Room? > > > Thanks, > > > Greg --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk@googlegroups.com To unsubscribe from this group, send email to rubyonrails-talk+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
