Rails 5 抛出中止：如何设置错误消息？

Question

Rails 引入了这种

throw(:abort)

语法，但现在如何获得有意义的销毁错误？

对于验证错误，可以这样做

if not user.save
  # => user.errors has information

if not user.destroy
  # => user.errors is empty

这是我的模型

class User

  before_destroy :destroy_validation,
    if: :some_reason

  private

  def destroy_validation
    throw(:abort) if some_condition
  end

Answer 1

您可以使用

errors.add

作为您的类方法。

用户型号：

def destroy_validation
  if some_condition
    errors.add(:base, "can't be destroyed cause x,y or z")
    throw(:abort)
  end
end

用户控制器：

def destroy
  if @user.destroy
    respond_to do |format|
      format.html { redirect_to users_path, notice: ':)' }
      format.json { head :no_content }
    end
  else
    respond_to do |format|
      format.html { redirect_to users_path, alert: ":( #{@user.errors[:base]}"}
    end
  end
end

Answer 2

Gonzalo S 的回答 非常好。但是，要清理代码，您可以考虑使用辅助方法。以下代码在 Rails 5.0 或更高版本中效果最佳，因为您可以使用

ApplicationRecord

模型。

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true

  private

  def halt(tag: :abort, attr: :base, msg: nil)
    errors.add(attr, msg) if msg
    throw(tag)
  end

end

现在你可以做：

class User < ApplicationRecord

  before_destroy(if: :some_reason) { halt msg: 'Your message.' }

  # or if you have some longer condition:
  before_destroy if: -> { condition1 && condition2 && condition3 } do
    halt msg: 'Your message.'
  end

  # or more in lines with your example:
  before_destroy :destroy_validation, if: :some_reason
  
  private

  def destroy_validation
    halt msg: 'Your message.' if some_condition
  end

end