ruby-on-rails - 如何在 Rails 5 中模拟 `OR` 关联的 `has_many` 条件？

Question

我要模拟OR has_many 的条件关联所以我不会丢失事件记录关联。我知道这可以使用 scope 来实现或实例方法，但在这种情况下，我将失去关联。

class Game < ActiveRecord::Base
  belongs_to :home_team, :class_name => "Team"
  belongs_to :away_team, :class_name => "Team"
  has_many :sponsors
end
class Sponsor < ActiveReord::Base
  belongs_to :game
end
class Team < ActiveRecord::Base
  has_many :away_games, :class_name => "Game", :foreign_key => "away_team_id"
  has_many :home_games, :class_name => "Game", :foreign_key => "home_team_id"

  # what I want here like:
  # has_many :games, :foreign_key => [:home_team_id, :away_team_id] 
  # so I could achieve without losing association helper:
  # has_many :sponsors through: :games
end

Answer 1

你可以这样做:

这里会先删除原来的作用域:team_id并使用 away_team_id或 home_team_id反而。

has_many :games, ->(team){ unscope(where: :team_id)
          .where('away_team_id = :team_id OR home_team_id = :team_id', team_id: team.id) }

has_many :sponsors, through: :games