4

我正在运行 ActiveRecord 3.2.6。鉴于我有这些模型定义：

我的发票模型

class Invoice < ActiveRecord::Base
  has_many :items, :autosave => true, :dependent => :delete_all
  attr_accessible :recipient_email

  # This is just a simple wrapper with allows me to build multiple
  # items at once and to specify them as a Hash instead of Item.new.
  def items=(ary)
    super ary.map{|item| item.is_a?(Hash) ? items.build(item) : item}
  end
end

我的项目模型

class Item < ActiveRecord::Base
  belongs_to :invoice

  attr_accessible :amount, :description, :invoice_id, :value
end

我的目标是将发票项目直接保存在模型中。当新创建发票时，这没有问题。一个电话Invoice#save!，一切都保存下来。

> i = Invoice.new(:recipient_email => "foobar@example.org")
> i.items = [{amount: 10, description: "Bottles of Milk", value: 0.40},
  {amount: 1, description: "Shipping fee to Antarctica", value: 217.38}]
> i.save!
  SQL (23.5ms)  INSERT INTO "invoices" [...]
  SQL (0.3ms)  INSERT INTO "items" [...]
  SQL (0.2ms)  INSERT INTO "items" [...]
 => true

但是，当我尝试更新Invoice已存在的项目时，它会在我保存新项目之前删除旧项目。

# Load invoice ID 1, with two items: ID 1 and ID 2.
> i = Invoice.find(1)

# It deletes the old items here
> i.items = [{amount: 10, description: "Less buggy objective relational mappers", value: 1337.00}]
  SQL (0.8ms)  DELETE FROM items WHERE id IN (1, 2)

# But it should delete the new items here, before inserting the new items,
# wrapping everything in a transaction.
> i.save!
  SQL (1.0ms)  INSERT INTO "items" [...]
   (192.6ms)  commit transaction

我如何告诉 ActiveRecord 仅在Invoice#save!被调用时才删除旧项目？或者这是 ActiveRecord 中的错误？

编辑：我的问题 - 澄清

我不希望在DELETE分配项目时运行查询 ( i.items = ...)，但在保存包含项目的发票时 ( invoice.save!)。它应该将旧项目标记为删除，将新项目标记为插入，然后在invoice.save!. 这可能与 ActiveRecord 吗？

编辑2：进一步澄清

由于有些人没有正确回答问题，因此需要进一步澄清。我必须承认，这很复杂。所以这就是实际发生的事情和我想要发生的事情之间的区别。

我想要的是

这不会发生。我希望它发生。这完全是虚构的。将其与上面的清单进行比较以查看差异。

# (1) Load invoice ID 1, with two items: ID 1 and ID 2.
> i = Invoice.find(1)

# (2) Assign new items, delete the old ones. New stuff exists in memory, not in database
> i.items = [{amount: 10, description: "Less buggy objective relational mappers", value: 1337.00}]

# (3) Save everything to database. Run queries.
> i.save!
   (0.0ms) begin transactions
  SQL (0.8ms)  DELETE FROM items WHERE id IN (1, 2)
  SQL (1.0ms)  INSERT INTO "items" [...]
   (192.6ms)  commit transaction

实际发生了什么

查询在DELETE点运行(2)。但它应该在点运行(3)。（与上面的列表比较）。

4

3 回答 3

0

由于您想在分配中附加操作，我相信这应该有效： 

  def items=(ary)
    super(ary.map{|item| item.is_a?(Hash) ? items.build(item) : item} + self.items)
  end
于 2012-07-07T12:45:14.650 回答
0

它将删除旧项目，因为您将关联配置为自动保存

has_many :items, :autosave => true, :dependent => :delete_all

删除自动保存并重试，它会工作。

于 2012-07-06T16:35:21.343 回答
0

您可以使用该选项配置您的关联，autosave: true并使用mark_for_destruction指定要销毁的每个项目save。

考虑到您的第二次编辑，您可以执行以下操作：

# (1) Load invoice ID 1, with two items: ID 1 and ID 2.
> i = Invoice.find(1)

# (2) Mark the old items to be destroyed on save. They are still in memory and in the database for now.
> i.items.each(&:mark_for_destruction)

# (3) Assign new items. New stuff exists in memory, not in database.
> i.items.build([{amount: 10, description: "Less buggy objective relational mappers", value: 1337.00}])

# (4) Delete the items which has been mark for destruction. Save everything to database. Run queries.
> i.save!
   (0.0ms) begin transactions
  SQL (0.8ms)  DELETE FROM items WHERE id IN (1, 2)
  SQL (1.0ms)  INSERT INTO "items" [...]
   (192.6ms)  commit transaction
于 2020-11-26T15:39:13.660 回答