Question

我正在与iPhone应用程序同步数据，因此了解哪些记录已“实际”更新以及哪些记录尚未更新非常重要。我有一个带有RelatedLink关联的Event模型：

在event.rb中：

has_many :related_links
accepts_nested_attributes_for :related_links, :reject_if => lambda { |a| a[:url].blank? && a[:id].blank? }, :allow_destroy => true

在我的活动表格上，当我什么都没改，包括RelatedLink字段时，我很好......我的活动模型没有更新任何内容。但是如果我在RelatedLink字段中输入url，则会更新Event对象上的“updated_at”。

UPDATE "events" SET "updated_at" = '2011-05-30 15:27:03.228435' WHERE "events"."id" = 1791

它应该这样吗？我可以阻止它被标记为脏并且正在更新吗？

Answer 1

如果父模型的属性没有改变，则记录不被视为脏，updated_at不应该改变。以此为例（Rails 3.2.3）

发布模型

class Post < ActiveRecord::Base
  attr_accessible :title, :body, :comments_attributes

  has_many :comments
  accepts_nested_attributes_for :comments
end

评论模型

class Comment < ActiveRecord::Base
  attr_accessible :body, :author
  belongs_to :post
end

Rails控制台测试（我粘贴时只保留相关输出）

1.9.3p194 :001 > p = Post.create :title => "Nested attributes", :body => "Nested attributes are awesome", :comments_attributes => [{ :body => "I agree", :author => "Bart" }]
=> #<Post id: 1, title: "Nested attributes", body: "Nested attributes are awesome", created_at: "2012-06-13 01:49:34", updated_at: "2012-06-13 01:49:34"> 

1.9.3p194 :002 > last_post = Post.last
=> #<Post id: 1, title: "Nested attributes", body: "Nested attributes are awesome", created_at: "2012-06-13 01:49:34", updated_at: "2012-06-13 01:49:34"> 

1.9.3p194 :003 > last_post.comments_attributes = [{:id => 1, :author => "Bort"}]
=> [{:id=>1, :author=>"Bort"}] 

1.9.3p194 :004 > last_post.changed?
=> false 

1.9.3p194 :005 > last_post.save
(0.1ms)  begin transaction
(0.7ms)  UPDATE "comments" SET "author" = 'Bort', "updated_at" = '2012-06-13 01:51:05.032862' WHERE "comments"."id" = 1
(250.1ms)  commit transaction
=> true 

1.9.3p194 :006 > last_post.updated_at
=> Wed, 13 Jun 2012 01:49:34 UTC +00:00

因此，您的案例中必须有其他内容导致在Event上触发更新。检查是否有callbacks可能正在执行此操作，并检查您的belongs_to方法是否未使用:touch选项定义。例如

belongs_to :event, :touch => true

Rails ActiveRecord：即使父属性未更改，accepts_nested_attributes_for是否将父记录标记为脏？

1 个答案: