Rails - 在自定义验证期间''无法使用默认proc'转储哈希值

Question

我有2个型号.User和Want.一个User has_many: Want.

该Want模型有一个单一的财产之外user_id,这就是name.

我在Want模型中编写了自定义验证,以便用户无法提交以创建具有相同名称的2个需求:

validate :existing_want

  private

    def existing_want
      return unless errors.blank?       
      errors.add(:existing_want, "you already want that") if user.already_wants? name
    end

该already_wants?方法位于用户模型中:

def already_wants? want_name
  does_want_already = false
  self.wants.each { |w| does_want_already = true if w.name == want_name }
  does_want_already
end

验证规范在我的模型测试中通过,但是当我尝试向以下create操作提交副本时,我的功能测试失败WantsController:

def create
    @want = current_user.wants.build(params[:want])
    if @want.save
      flash[:success] = "success!"
      redirect_to user_account_path current_user.username
    else
      flash[:validation] = @want.errors
      redirect_to user_account_path current_user.username
    end
  end

我得到的错误: 无法使用默认proc转储哈希

没有堆栈跟踪导致我的代码.

我已将问题缩小到这条线:

self.wants.each { |w| does_want_already = true if w.name == want_name }

如果我只是返回,true不管我想在视图中显示的错误.

我不明白？怎么了？为什么它如此神秘？

谢谢.

Answer 1

如果没有堆栈跟踪(它是否在任何地方引导,或者只是没有出现？),很难知道究竟发生了什么,但是这里是如何在干净的环境中重现这个错误:

# initialize a new hash using a block, so it has a default proc
h = Hash.new {|h,k| h[k] = k } 

# attempt to serialize it:
Marshal.dump(h)
#=> TypeError: can't dump hash with default proc

Ruby无法序列化procs,因此无法正确重构该序列化哈希值,从而导致错误.

如果您有理由确定该行是您遇到问题的根源,请尝试重构它以查看是否能解决问题.

def already_wants? want_name
  wants.any? {|want| want_name == want.name }
end

要么

def already_wants? want_name
  wants.where(name: want_name).count > 0
end