如何在 Rails 5 中模拟“has_many”关联的“OR”条件

Question

我想模拟has_many关联的OR条件，这样我就不会丢失活动的记录关联。我知道这可以使用scope或实例方法来实现，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

你可以做这样的事情：

在这里，它将首先删除原始作用域:team_id，并改用away_team_id或home_team_id。

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