:autosave 忽略了 has_many 关系——我错过了什么? [英] :autosave ignored on has_many relation -- what am I missing?
问题描述
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 为真时，所有子项都会被保存，无论它们是否是新记录:
When :autosave is true all children is saved, no matter whether they are new records:
但是当我更新 Item 并保存其父 Collection 时，Item 的更新属性不会被保存:
But when I update an Item and save its parent Collection, the Item's upated attributes don't get saved:
> 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?
我使用的是 Rails 3.2.5 和 Ruby 1.9.2.
I'm using Rails 3.2.5 and Ruby 1.9.2.
所以我在 ActiveRecord 的源代码中做了一些挖掘.我们可以得到 c 的自动保存关联:
So I've done some digging about in the source of ActiveRecord. We can get hold of c's autosave assocations:
> 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>]
我认为这说明关联已设置为自动保存.
I think this illustrates that the association has been set up for autosaving.
然后我们就可以得到c对应的关联实例:
We can then get the instance of the association corresponding to 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这个关联关联的实际对象:
We can then find the actual objects that are associated via this association:
> 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">]
此处找到的对象没有我之前所做的更新.
The object found here does not have update that I'd made earlier.
推荐答案
问题出在这里
i = c.items.first
这一行从数据库中提取正确的项目，但没有将其附加到集合 c.它是与对象不同的 ruby 对象
This line pulls the correct item from the database, but doesn't attach it to the collection c. It is a distinct ruby object from the object
i = c.items[0]
如果您用第二行替换第一行，您的示例将起作用.
If you replace the first line with the second your example will work.
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