:在has_many关系上忽略了自动保存 - 我错过了什么？

Question

我有一对班级:

class Collection < ActiveRecord::Base                                                                                                                                                                                                         
  has_many :items, autosave: true
end

class Item < ActiveRecord::Base
  belongs_to :collection
end

来自文档:

当:autosave为true时,无论是否为新记录,都会保存所有子项:

但是当我更新Item并保存其父级时Collection,Item不会保存已升级的属性:

 > c = Collection.first
 => #<Collection id: 1, name: "collection", created_at: "2012-07-23 00:00:10", updated_at: "2012-07-23 00:00:10"> 
 > i = c.items.first
 => #<Item id: 1, collection_id: 1, name: "item1", created_at: "2012-07-23 00:00:25", updated_at: "2012-07-23 00:00:25"> 
 > i.name = 'new name'
 => "new name" 
 > c.save
 => true 
 > Collection.first.items
 => [#<Item id: 1, collection_id: 1, name: "item1", created_at: "2012-07-23 00:00:25", updated_at: "2012-07-23 00:00:25">]

那么,我错过了什么？

我正在使用Rails 3.2.5和Ruby 1.9.2.

---

所以我在ActiveRecord的源代码中做了一些挖掘.我们可以掌握c自动保存关联:

 > c.class.reflect_on_all_autosave_associations
 => [#<ActiveRecord::Reflection::AssociationReflection:0x007fece57b3bd8 @macro=:has_many, @name=:items, @options={:autosave=>true, :extend=>[]}, @active_record=Collection(id: integer, name: string, created_at: datetime, updated_at: datetime), @plural_name="items", @collection=true, @class_name="Item", @klass=Item(id: integer, collection_id: integer, name: string, created_at: datetime, updated_at: datetime), @foreign_key="collection_id", @active_record_primary_key="id", @type=nil>]

我认为这表明该协会已经建立了自动保护.

然后我们可以得到对应的关联实例c:

 > a = c.send :association_instance_get, :items
 => #<ActiveRecord::Associations::HasManyAssociation:0x007fece738e920 @target=[#<Item id: 1, collection_id: 1, name: "item1", created_at: "2012-07-23 00:00:25", updated_at: "2012-07-23 00:00:25">], @reflection=#<ActiveRecord::Reflection::AssociationReflection:0x007fece57b3bd8 @macro=:has_many, @name=:items, @options={:autosave=>true, :extend=>[]}, @active_record=Collection(id: integer, name: string, created_at: datetime, updated_at: datetime), @plural_name="items", @collection=true, @class_name="Item", @klass=Item(id: integer, collection_id: integer, name: string, created_at: datetime, updated_at: datetime), @foreign_key="collection_id", @active_record_primary_key="id", @type=nil>, @owner=#<Collection id: 1, name: "collection", created_at: "2012-07-23 00:00:10", updated_at: "2012-07-23 00:00:10">, @updated=false, @loaded=true, @association_scope=[#<Item id: 1, collection_id: 1, name: "item1", created_at: "2012-07-23 00:00:25", updated_at: "2012-07-23 00:00:25">], @proxy=[#<Item id: 1, collection_id: 1, name: "item1", created_at: "2012-07-23 00:00:25", updated_at: "2012-07-23 00:00:25">], @stale_state=nil> 

然后,我们可以找到通过此关联关联的实际对象:

 > a.target
 => [#<Item id: 1, collection_id: 1, name: "item1", created_at: "2012-07-23 00:00:25", updated_at: "2012-07-23 00:00:25">]

这里找到的对象没有我之前做的更新.

Answer 1

这里的问题是这条线

 i = c.items.first

此行从数据库中提取正确的项目,但不将其附加到集合c.它是一个与物体不同的红宝石物体

i = c.items[0]

如果您用第二行替换第一行,您的示例将起作用.