Rails 3.1限制用户创建的对象

Question

我想限制用户可以创建的模型对象的数量.我已经尝试过以下但它不起作用.我理解rails 3.1中发生了一些变化,现在还不确定如何实现.

class User < ActiveRecord::Base
  has_many :things, :limit => 5, :dependent => :destroy # This doesn't work
end

class Things <ActiveRecord::Base
  belongs_to :user
end

Answer 1

尝试这样的事情:

class User < ActiveRecord::Base
  has_many :things
end

class Things <ActiveRecord::Base
  belongs_to :user
  validate :thing_count_within_limit, :on => :create

  def thing_count_within_limit
    if self.user.things(:reload).count >= 5
      errors.add(:base, "Exceeded thing limit")
    end
  end
end

编辑:更新为Rails 3