Rails 3 事务，回滚一切

Question

class Bear < ActiveRecord::Base
    def feed!
      self.transaction do
          raise Exception unless self.foods_eaten << Food.new(:name => "fish")
          self.fed_at = Time.now
          save!
       end
    end
end

class Hippo < ActiveRecord::Base
    def wash!
        self.transaction do
            @soap.inventory -= 1
            @soap.save!
            self.washed_at = Time.now
            save!
        end
    end
end

class ZookeeperController < ApplicationController

    def chores
        @zookeeper = Zookeeper.find(params[:id])
        Animal.transaction do
            begin
                @hippo.wash!
                @bear.feed!    # => FAIL AT THIS LINE
                @zookeeper.finished_at = Time.now
                @zookeeper.save!
                redirect_to chores_completed_path
            rescue Exception => e
                 render "new_chores"
            end
        end
    end
end

如果 Zookeeper#chores 被调用并且 @bear.feed! 失败并引发异常，那么一切都会回滚吗？

也欢迎任何有关如何改进此代码的其他建议。

Answer 1

看来我要做的就是手动引发 ActiveRecord::Rollback，否则它将无法按预期工作。 ActiveRecord::Rollback 是唯一不会导致屏幕转储的方法。 http://api.rubyonrails.org/classes/ActiveRecord/Rollback.html

它会像这样工作是有道理的，但实际上并不是我直观地认为它会如何工作。如果我错了，请纠正我。

所以新代码看起来像这样：

class ZookeeperController < ApplicationController

    def chores
        @zookeeper = Zookeeper.find(params[:id])
        Animal.transaction do
            begin
                @hippo.wash!
                @bear.feed!    # => FAIL AT THIS LINE
                @zookeeper.finished_at = Time.now
                @zookeeper.save!
                redirect_to chores_completed_path
            rescue Exception => e
                 @_errors = true
                 render "new_chores"
            end
            raise ActiveRecord::Rollback if @_errors
        end
    end
end