ruby-on-rails - state_machine 仅适用于新记录

Question

我似乎无法获得 state_machine gem ( http://github.com/pluginaweek/state_machine/ ) 来处理现有记录(它可以在新记录上正常工作)。

这是我的模型:

class Comment < ActiveRecord::Base
  state_machine :state, :initial => :pending do
    event :publish do
      transition all => :published
    end
  end
end

这是一个演示该问题的 IRB session (我做了 ActiveRecord::Base.logger = Logger.new(STDOUT) 以使其更易于阅读):

>> c = Comment.new
=> #<Comment id: nil, song_id: nil, author: nil, body: nil, created_at: nil, updated_at: nil, state: "pending">
>> c.state
=> "pending"
>> c.publish
  Comment Create (0.6ms)   INSERT INTO "comments" ("updated_at", "body", "author", "song_id", "created_at", "state") VALUES('2009-11-02 02:44:37', NULL, NULL, NULL, '2009-11-02 02:44:37', 'published')
=> true
>> Comment.last.state
  Comment Load (0.4ms)   SELECT * FROM "comments" ORDER BY comments.id DESC LIMIT 1
=> "published"
>> c = Comment.create
  Comment Create (0.5ms)   INSERT INTO "comments" ("updated_at", "body", "author", "song_id", "created_at", "state") VALUES('2009-11-02 02:44:47', NULL, NULL, NULL, '2009-11-02 02:44:47', 'pending')
=> #<Comment id: 4, song_id: nil, author: nil, body: nil, created_at: "2009-11-02 02:44:47", updated_at: "2009-11-02 02:44:47", state: "pending">
>> c.publish
=> true
>> c.save
=> true
>> Comment.last.state
  Comment Load (0.4ms)   SELECT * FROM "comments" ORDER BY comments.id DESC LIMIT 1
=> "pending"

即，当我 publish 时一切正常未保存的评论，但当我尝试发布已保存的评论时，没有任何反应。

另一个编辑:也许是问题的根源？

=> true
>> a = Comment.last
  Comment Load (1.3ms)   SELECT * FROM "comments" ORDER BY comments.id DESC LIMIT 1
=> #<Comment id: 3, song_id: nil, author: nil, body: nil, created_at: "2009-11-03 03:03:54", updated_at: "2009-11-03 03:03:54", state: "pending">
>> a.state
=> "pending"
>> a.publish
=> true
>> a.state
=> "published"
>> a.state_changed?
=> false

即，即使状态实际上已经改变，state_changed?返回 false，因此当我调用 save 时 Rails 不会更新相应的数据库行.

它在我关闭部分更新时有效，但在我尝试 state_will_change! 时无效:

>> Comment.partial_updates = false
=> false
>> c = Comment.create
  Comment Create (0.5ms)   INSERT INTO "comments" ("updated_at", "body", "author", "song_id", "created_at", "state") VALUES('2009-11-07 05:06:49', NULL, NULL, NULL, '2009-11-07 05:06:49', 'pending')
=> #<Comment id: 7, song_id: nil, author: nil, body: nil, created_at: "2009-11-07 05:06:49", updated_at: "2009-11-07 05:06:49", state: "pending">
>> c.publish
  Comment Update (0.9ms)   UPDATE "comments" SET "created_at" = '2009-11-07 05:06:49', "author" = NULL, "state" = 'published', "body" = NULL, "song_id" = NULL, "updated_at" = '2009-11-07 05:06:53' WHERE "id" = 7
=> true
>> Comment.last.state
  Comment Load (0.5ms)   SELECT * FROM "comments" ORDER BY comments.id DESC LIMIT 1
=> "published"
>> Comment.partial_updates = true
=> true
>> c = Comment.create
  Comment Create (0.8ms)   INSERT INTO "comments" ("updated_at", "body", "author", "song_id", "created_at", "state") VALUES('2009-11-07 05:07:21', NULL, NULL, NULL, '2009-11-07 05:07:21', 'pending')
=> #<Comment id: 8, song_id: nil, author: nil, body: nil, created_at: "2009-11-07 05:07:21", updated_at: "2009-11-07 05:07:21", state: "pending">
>> c.state_will_change!
=> "pending"
>> c.publish
=> true
>> c.save
=> true
>> Comment.last.state
  Comment Load (0.5ms)   SELECT * FROM "comments" ORDER BY comments.id DESC LIMIT 1
=> "pending"

编辑:

更多怪事:

>> a = Comment.last
  Comment Load (1.2ms)   SELECT * FROM "comments" ORDER BY comments.id DESC LIMIT 1
=> #<Comment id: 5, song_id: nil, author: nil, body: nil, created_at: "2009-11-02 06:33:19", updated_at: "2009-11-02 06:33:19", state: "pending">
>> a.state
=> "pending"
>> a.publish
=> true
>> a.state
=> "published"
>> a.save
=> true
>> a.id
=> 5
>> Comment.find(5).state
  Comment Load (0.3ms)   SELECT * FROM "comments" WHERE ("comments"."id" = 5) 
=> "pending"

比较:

>> a = Comment.last
  Comment Load (0.3ms)   SELECT * FROM "comments" ORDER BY comments.id DESC LIMIT 1
=> #<Comment id: 5, song_id: nil, author: nil, body: nil, created_at: "2009-11-02 06:33:19", updated_at: "2009-11-02 06:33:19", state: "pending">
>> a.state = "published"
=> "published"
>> a.save
  Comment Update (0.6ms)   UPDATE "comments" SET "state" = 'published', "updated_at" = '2009-11-02 08:29:34' WHERE "id" = 5
=> true
>> a.id
=> 5
>> Comment.find(5).state
  Comment Load (0.4ms)   SELECT * FROM "comments" WHERE ("comments"."id" = 5) 
=> "published"

Answer 1

3 年后我遇到了同样的问题，所以值得在这里回答以节省其他人的时间。

您的表中需要有名为“state”的列，这样 state_machine 才能使状态持久化。

只需将它添加到您的迁移中 - t.string :state