statemachine，條件轉換

Question

我目前使用Workflow。現在

class Link < ActiveRecord::Base 
    include Workflow 
    workflow do 
    state :new do 
     event :process, :transitions_to => :checking #checking http_response_code & content_type 
    end 

    state :checking do 
     event :process, :transitions_to => :fetching_links # fetching all links 
    end 
    state :fetching_links do 
     event :process, :transitions_to => :checking #ready for next check 
    end 
    end 
end 

，我可以這樣做：

l = Link.new 
l.process! 
l.process! 
l.process! 
l.process! 
# n times l.process! (in a loop, or cron job for example) 

但它可偏偏，有些鏈接將不響應，或者給我一個無效響應德寧檢查過程。

我如何有條件地切換到另一個狀態？

我的意思是這樣的：

class Link < ActiveRecord::Base 
    include Workflow 
    workflow do 
    state :new do 
     event :process, :transitions_to => :checking #checking http_response_code & content_type 
    end 

    state :checking do 
     event :process, :transitions_to => :fetching_links # if all is fine 
     event :process, :transitions_to => :failded # if something goes wrong 
    end 
    state :fetching_links do 
     event :process, :transitions_to => :checking #ready for next check 
    end 
    end 
end 

Answer 1

我不知道您的動作將被執行。 on_entry或on_exit的狀態。

我認爲最好的是，當轉換到我的下一個狀態時，如果發生錯誤，我可以轉換到另一個狀態，例如， :failed。我沒有嘗試過，但我發現你可以將halt過渡到一個狀態，這意味着轉換失敗。

例如：

state :checking do 
    event :process, :transitions_to => :fetching_links do 
    fetch_links 
    halt if fetch_links_failed? 
    end 
end 

你會使用如下：

l.process 
l.halted? => true # if fetching_links failed 

這是否幫助？