Rails has_many, build, inverse_of

Question

我有 2 个这样的模型：

class User < ActiveRecord::Base
    has_many :user_services, :inverse_of => :user

    validates_length_of :user_services, :maximum => 3
end

class UserService < ActiveRecord::Base
    belongs_to :user, :inverse_of => :user_services

    validates_associated :user
end

我想做这样的事情：

user_service = user.user_services.build(...)
if user_service.save
...

但它会引发“堆栈级别太深”错误。我假设是因为 validates_associated 与 inverse_of 相结合。有谁知道为什么会这样？

直接在用户对象而不是 user_service 对象上调用 save 似乎可行，但我想知道是否有办法反过来实现这些。

谢谢！

Answer 1

发生这种情况是因为您的验证具有循环依赖关系。

validates_length_of :user_services
validates_associated :user

http://api.rubyonrails.org/classes/ActiveRecord/Validations/ClassMethods.html#method-i-validates_associated

更新

如果你用这种方式重写你的代码，你可以移除循环依赖：

class User < ActiveRecord::Base
  has_many :user_services, :inverse_of => :user
  validates_length_of :user_services, :maximum => 3
end

class UserService < ActiveRecord::Base
  belongs_to :user, :inverse_of => :user_services

  def user_services_amount
     return 0 if self.user.nil?
     self.user.user_services.length
  end

  validates :user_services_amount, :inclusion => { :in => 0..3 }
end