ruby - 一对一的 DataMapper 关联

Question

我是 DataMapper 的新手，我正在尝试为以下场景创建模型:

我有许多用户(有用户名、密码等)，他们也可以是球员或裁判或两者兼而有之(因此单表继承不是一个选项)。基本模型是:

class User
  include DataMapper::Resource
  property :id, Serial
  # Other user properties go here  
end

class Player
  include DataMapper::Resource
  property :id, Serial
  # Other player properties go here
  # Some kind of association goes here
end

class Referee
  include DataMapper::Resource
  property :id, Serial
  # Other referee properties go here
  # Some kind of association goes here
end

DataMapper.finalize

不过，我不确定要为 Player 和 Referee 添加什么样的关联。使用 belongs_to :user，多个玩家可以与同一用户相关联，这在我的上下文中没有意义。在 RDBMS 术语中，我想我想要的是对 Players 和 Referees 表中外键的唯一约束。

我如何在我的 DataMapper 模型中完成这项工作？我是否必须自己在验证中执行检查？

Answer 1

您可以通过不同的方式来做到这一点。这是一个选项:

class User
  include DataMapper::Resource
  property :id, Serial
  # Other properties...
  has 1, :referee, :required => false
  has 1, :player, :required => false
end

class Referee
  include DataMapper::Resource
  # DON'T include "property :id, Serial" here
  # Other properties...
  belongs_to :user, :key => true
end
class Player
  include DataMapper::Resource
  # DON'T include "property :id, Serial" here
  # Other properties...
  belongs_to :user, :key => true
end

对裁判/球员模型采取行动，例如:

u = User.create(...)
u.referee = Referee.create(...)
u.player = Player.create(...)

u.player.kick_ball() # or whatever you want to call
u.player.homeruns
u.referee.flag_play() # or whatever.

看看这是否有效。我还没有实际测试过，但应该不错。