Question

用户只能有两种类型的订阅：DailySubscription和WeeklySubscription。当用户处于新的编辑操作时，我希望他们检查他们想要获得的任何订阅。

我很喜欢使用嵌套字段（根据Ryan Bates的截屏视频here）但我认为当我添加继承时，它确实使事情变得复杂。 有更好的方法吗？

class User < ActiveRecord::Base
    has_many :subscriptions
end

class Subscription < ActiveRecord::Base
    belongs_to :user
    # type field is defined in the migration for Single Table Inheritance
end

class DailySubscription < Subscription
    # Business logic here 
end

class WeeklySubscription < Subscription
   # Different business logic here 
end

我对控制器的初步努力是古怪的：

class UsersController < ApplicationController
  def new
    @user = User.new
    # I can't use @user. subscriptions.build as Rails doesn't 
    # know what type of model to add! 
    @user.subscriptions = [DailySubscription.new, WeeklySubscription.new]
  end

  ...

end

我认为我在概念上确实错过了一些东西，但我无法弄明白。救命啊！

Answer 1

根据您的描述，您的用户只有两种可能的订阅选择：每日和/或每周。因此，你不需要有一个has_many关联，因为两个has_one就足够了（注意下面的多态可订阅：

class User < ActiveRecord::Base
  has_one :daily_subscription, :as => :subscribeable
  has_one :weekly_subscription, :as => :subscribeable
end

class Subscription < ActiveRecord::Base
  belongs_to :subscribeable, :polymorphic => true
  # type field is defined in the migration for Single Table Inheritance
end

class DailySubscription < Subscription
  # Business logic here 
end

class WeeklySubscription < Subscription
  # Different business logic here 
end

此外，对于控制器，您只需要初始化User。初始化时，@ user.daily_subscription和weekly_subscription将为.blank确定为null？方法。当您继续在create方法中创建用户时，您需要使用相应订阅的实例填充这些字段。

class UsersController < ApplicationController
  def new
   @user = User.new
   # bam -- youre done.

 end

...

端

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