habtm or two foreign keys?

rubyonrails-talk
1

Somehow I keep running into this problem in different projects ..

Say I want to represent soccer matches. A Match is associated with exactly two Teams, and keeps the score each team achieved. I see two choices:

a) add two foreign keys to Match and have it belong_to :team_a and :team_b

pro: it is easy to match score_a to team_a and score_b to team_b, and it is innately impossible to associate too many teams

con: I would need two rather ugly has_many associations in the Team model, as in "has_many :team_a_matches / has_many :team_b_matches" (right?)

b) use habtm

pro: nice and clean associations

con: associating score_a and score_b attributes in the Match model with exactly the right team from Match#teams gets convoluted and error-prone, and association validation is a bit more involved

How would you proceed? Am I missing a third option?

Thanks in advance, Jan

2

I think you want this:

class Match < ActiveRecord::Base   belongs_to :team end

class Team < ActiveRecord::Base   has_many :games, :foreign_key => :away_team   has_many :games, :foreign_key => :home_team end

Then you can do Team.find(1).games #displays home and away games Game.find(1).home_team Game.find(1).away_team

ESPNDev

3

Thanks for your input! I don't really have the distinction into home and away teams - I'm building a small app for the upcoming Euro Cup - but it may be best to pretend I had and be done with it.