Question

我正在使用Transitions gem在我的模型设置中创建状态机，如下所示：

require 'transitions'

class Batch < ActiveRecord::Base
  include Transitions

  state_machine do
    state :pending
    state :completed


    event :change_state do 
      transitions :to => :completed, :from => [:pending] 
    end

  end


end

我想查询模型以获取具有特定状态的所有记录，例如：

Batch.where :current_state => :pending

但这似乎不起作用，我在查找文档方面遇到了麻烦。有谁知道如何做到这一点？（我确信它似乎无法找到它）提前谢谢！

修改

运行tail -n development.log给了我：

ActionView::Template::Error (SQLite3::SQLException: no such column: batches.current_state: SELECT "batches".* FROM "batches" WHERE "batches"."user_id" = 1 AND "batches"."current_state" = 'pending'):
    3: <%= link_to 'New Batch', new_batch_path %>
    4: 
    5:                                                                      
    6: <% unless @pending_batches.length < 1 %>
    7:  You have <%= @pending_batches.length %> batches pending on these urls:
    8:  <% @pending_batches.each do |batch| %>
    9:      <%= batch.url %>        
  app/views/batches/index.html.erb:6:in `_app_views_batches_index_html_erb___355556540_17724200__911230187'
  app/controllers/batches_controller.rb:8:in `index'

Rendered /Users/dshipper/.rvm/gems/ruby-1.9.2-p180@artsicle/gems/actionpack-3.0.9/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.5ms)
  Batch Load (0.5ms)  SELECT "batches".* FROM "batches" WHERE "batches"."user_id" = 1 AND "batches"."current_state" = 'pending'
SQLite3::SQLException: no such column: batches.current_state: SELECT "batches".* FROM "batches" WHERE "batches"."user_id" = 1 AND "batches"."current_state" = 'pending'
Rendered /Users/dshipper/.rvm/gems/ruby-1.9.2-p180@artsicle/gems/actionpack-3.0.9/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (6.6ms)
Rendered /Users/dshipper/.rvm/gems/ruby-1.9.2-p180@artsicle/gems/actionpack-3.0.9/lib/action_dispatch/middleware/templates/rescues/template_error.erb within rescues/layout (16.1ms)
  SQL (0.2ms)   SELECT name
 FROM sqlite_master
 WHERE type = 'table' AND NOT name = 'sqlite_sequence'

  Batch Load (0.3ms)  SELECT "batches".* FROM "batches" HAVING "batches"."current_state" = 'pending'
SQLite3::SQLException: a GROUP BY clause is required before HAVING: SELECT "batches".* FROM "batches" HAVING "batches"."current_state" = 'pending'

运行grep'current_state db / schema.rb'不会返回任何结果。我希望尽管因为没有名为current_state的实际列，但是记录的状态由状态机管理（不确定它存储状态的确切位置）。

Answer 1

我也正在研究状态机，虽然我还没有在我的项目中实现它，但我发现这可能会有所帮助。

确保您的gemfile包含

gem "transitions", :require => ["transitions", "active_record/transitions"]

确保您的模型
```
include ActiveRecord::Transitions
```
而不仅仅是
```
include Transitions
```
并且它有一个名为'state'的列，因为这是状态持久化的地方。

这个问题似乎已在此处记录：

http://dev.netizer.pl/transitions-state-machine-for-rails-3.html/comment-page-1#comment-41

github上的文档也概述了Rails的设置

http://github.com/qoobaa/transitions

使用Rails

这进入你的Gemfile：

gem“transitions”，：require =＆gt; [“transition”，“active_record / transitions”]

...这是您的AR模型：

包括ActiveRecord :: Transitions

关于持久性的说明

用于保持模型状态的属性被命名为state（真的！），它应该是一个足够宽的字符串列，以适合您最长的状态名称。还应该提到#save！在每次成功的活动后都会被召唤。

希望这有帮助，祝你好运！

按状态机状态Rails查询3

1 个答案:

http://github.com/qoobaa/transitions

使用Rails