Question

What is the best way to achieve a has two association with activerecord?

I have a Team and Game models. Each Team will have_many games @team.games. A Game will have two teams @game.hosting_team and @game.opposing_team.

I started out with two belongs_to/has_one associations but then @team.games would only return their home games.

The other option I can think of is using a HABTM and use a validator to ensure there are only records. The only thing missing is keeping track of the home team. It seems like I need a has many through association but I’m not exactly sure…

Thanks for your help.

This is an example of how the two has_many associations look. The problem here is I would have to call team.games and team.opponents to get a full list of their games

class Team < ActiveRecord::Base
  has_many :games
  has_many :opponents, :class_name => "Team"#, :foreign_key => ""
end

class Game < ActiveRecord::Base
  belongs_to :team, :class_name => "Team" #, :foreign_key => "team_id"
  belongs_to :opponent, :class_name => "Team" #, :foreign_key => "opponent_id"
end

I’d like something like this but this obviously isn’t how belongs_to works.

class Team < ActiveRecord::Base
  has_many :games
end

class Game < ActiveRecord::Base
  belongs_to :hosting_team
  belongs_to :opposing_team
end

My desired api would look like this.

@team.games # return all games home or away
@game.hosting_team # Team
@game.opposing_team # Team

Answer 1

You can probably still model it with the bt/ho associations, and set up games as an accessor method on the team instead of as an association:

class Team < ActiveRecord::Base
  def games
    Game.find(:conditions => ["home_team_id = ? OR away_team_id = ?", id, id])
  end
end