我要限制模式的数量对象的用户可以创建。我试过下面，但它不能正常工作。我明白了一些变化发生在轨3.1和不知道现在该怎么做到这一点。

 类用户的LT;的ActiveRecord :: Base的
  的has_many：事情，：上限=＆GT; 5日：依赖=＆GT; ：摧毁＃这不工作
结束

一流的物联网＆LT;的ActiveRecord :: Base的
  belongs_to的：用户
结束
 

解决方案

尝试是这样的：

 类用户的LT;的ActiveRecord :: Base的
  的has_many：事
结束

一流的物联网＆LT;的ActiveRecord :: Base的
  belongs_to的：用户
  验证：thing_count_within_limit，：上=＆GT; ：创建

  高清thing_count_within_limit
    如果self.user.things（：重装）.Count之间的＆GT; = 5
      errors.add（：基地，超出限额的东西）
    结束
  结束
结束
 

修改：更新的Rails的3

I would like to limit the number of model Objects a user can create. I've tried the below but it is not working. I understand some changes have happened in rails 3.1 and not sure how to accomplish this now.

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

class Things <ActiveRecord::Base
  belongs_to :user
end

Try something like this:

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

Edit: updated for Rails 3