AASM 状态机异常处理示例？

Question

我目前正在研究 class，它基本上是在做以下事情：

模型已创建
获取数据（事件"get_things!"）
- 如果发生异常，状态应该变成"failed"
- 如果成功，状态应该是"finished"

我尝试按如下方式实现它：

class Fetcher < ActiveRecord::Base
  include AASM

  aasm do
    state :created, initial: true
    state :success, :failed

    event :succeed do
      transitions from: :created, to: :success
    end

    event :fail do
      transitions from: :created, to: :failed
    end
  end

  def read_things!(throw_exception = false)
    begin
      raise RuntimeError.new("RAISED EXCEPTION") if throw_exception
      self.content = open("https://example.com?asd=324").read
      self.succeed!
    rescue => e
      self.fail!
    end
  end
end

a = Fetcher.new
a.read_things!(throw_exception = true)
=> state should be failed

a = Fetcher.new
a.read_things!(throw_exception = false)
=> state should be succeess

它有效，但看起来不太好做...

我更喜欢自述文件中提到的类似错误处理的东西

event :read_things do
  before do
    self.content = open("https://example.com?asd=324").read
    self.succeed!
  end
  error do |e|
    self.fail!
  end
  transitions :from => :created, :to => :success
end

但我不知道这是否真的是这里的最佳实践？

我也有很多事件，它们的行为都应该像上面显示的我提到的错误处理，我看到我可以以某种方式使用 error_on_all_events - 但没有找到任何关于它的文档？

有什么想法吗？谢谢！

编辑： 更改了一些小部分以消除混淆。

Answer 1

首先，方法名是fetch!还是read_things？在任何情况下，您都不想传递布尔参数来确定是否引发异常。如果引发异常，那么您的 rescue 将拾取它：

def read_things
  self.content = open("https://example.com?asd=324").read
  succeed!
rescue => e
  # do something with the error (e.g. log it), otherwise remove the "=> e"
  fail!
end

I would prefer something like the error handling which is mentioned in the readme

您的错误处理示例实际上是很好的做法（进行了一些小的修改）：

event :read_things do
  before do
    self.content = open("https://example.com?asd=324").read
  end
  error do |e|
    fail! # the self is optional (since self is your Fetcher object)
  end
  transitions from: :created, to: :success
end

实践中：

a = Fetcher.new
a.read_things!

如果self.content没有抛出异常那么状态将从created转换到success（不需要直接调用succeed!），否则错误处理程序将调用 fail! 转换，它将尝试将状态转换为 failed.

编辑：

error_on_all_events 回调与 AASM 的用法示例：

aasm do
  error_on_all_events :handle_error_for_all_events

  state :created, initial: true
  state :success, :failed

  event :succeed do
    transitions from: :created, to: :success
  end

  event :fail do
    transitions from: :created, to: :failed
  end
end

def handle_error_for_all_events
  # inspect the aasm object and handle error...
  puts aasm
end

AASM 状态机异常处理示例？

AASM state machine exception handling example?

ruby-on-rails

ruby-on-rails-3

state-machine

aasm