ruby-on-rails - 如何避免 ActiveRecord 模型双重保存？

Question

“一”型

class One < ActiveRecord::Base
  before_save :do_stuff

  private
    def do_stuff
      two = Two.find(8)
      two.field2 = 'Value'
      two.save!
    end
end

“二”型

class Two < ActiveRecord::Base
  before_save :do_stuff

  private
    def do_stuff
      one = One.find(7)
      one.field2 = 'SomeValue'
      one.save!
    end
end

执行:

two = Two.find(1)
two.somefield = 'NewVal'
two.save!

无限循环将开始。实现两个必须在 before_save 回调中相互更改的模型的最 ruby​​-on-rails 方法是什么？

Answer 1

在极少数情况下您需要这样做，您可能希望禁用您的 before_save使用 attr_accessor 过滤或将其移至 after_save块以避免循环。

例如:

class One < ActiveRecord::Base
  attr_accessor :not_doing_stuff
  before_save :do_stuff,
    :unless => :not_doing_stuff

private
  def do_stuff
    two = Two.find(8)
    two.field2 = 'Value'
    two.save!
  end
end

您至少要禁用其中之一的触发器:

class Two < ActiveRecord::Base
  before_save :do_stuff

private
  def do_stuff
    one = One.find(7)
    one.not_doing_stuff = true
    one.field2 = 'SomeValue'
    one.save!
  end
end

像这样的事情总是很丑陋，所以尽量避免它，除非你想不出其他办法。如果您需要它，请确保您编写了足够的单元测试，以确保它不会在某些边缘情况下陷入无限循环。