更新has_many / belong_to关系中大量关联对象的行（Rails 4，PostgreSQL 9.4，activeadmin） [英] Update massive number of rows of associated objects in has_many/belong_to relations (Rails 4, postgresql 9.4, activeadmin)

问题描述

在创建模型交易时，我使用after_create在DealPrize表上创建奖品。

交易和DealPrize有一个属于/ has_many关系：一个交易具有

它的工作原理是这样的：在我的管理面板（使用activeadmin）中，在Deal内，我有一个'prize列-number'，然后我使用after_create，以便每次管理员创建新交易时，应用程序都会使用这award_number列，并在DealPrize表内创建此数量的奖品（插入必要的行=>经常超过300,000） 。

因此，我创建了一个交易，该应用自动创建了大量关联对象（奖品），例如300,000个。

问题是我希望两天后将奖金数从300,000更改为272,000（少奖）或324,000（更多奖）。

如何更新创建的交易并告诉我的Rails应用更新关联数量ted奖品（删除一些或添加一些）而又不让其消失并重新创建整个Deal对象？

此外，我还需要一种快速的方法（例如我使用的一种方法）创建Deal =>原始sql和事务，因为一次创建的行数非常高。）

modals Deals.rb

  has_many：deal_prizes，从属：：delete_all 
 
 after_create：create_deal_prizes 
 
 CONNECTION = ActiveRecord :: Base.connection.raw_connection 
 
 def create_deal_prizes 
 begin 
 CONNECTION.describe_prepared（'yokoatxz'）
急救PG :: InvalidSqlStatementName 
 CONNECTION.prepare（'yokoatxz'，'INSERT INTO deal_prizes（deal_id，created_at，updated_at，admin_user_id）值（$ 1，$ 2，$ 3，$ 4）'）
结束
 
 Deal.transaction做
 self.prizes_number.times做| i | 
 CONNECTION.exec_prepared（'yokoatxz'，[{值：self.id}，
 {值：'2009-01-23 20:21:13'}，
 {值：' 2009-01-23 20:21:13'}，
 {值：self.admin_user_id} 
]）
结束
结束
结束
  

感谢您的帮助，Mathieu

解决方案

好吧，我认为，如果您只是想更改deal_prizes的数量，则可以在Deal上使用before_save回调来测试priest_number和prize_number_was之间的差异，并适当地发出插入或删除语句。 / p>

我希望对删除操作执行以下操作：

  deal_prizes.limit（prize_number_was-奖品编号）.delete_all 
  

...如果

您可能想在deal_prizes上使用范围：

  def self.deletable 
其中（：taken => false）
 end 
  

...以应用可删除行的条件，然后将其合并到交易关联中...

  has_many：deletable_deal_prizes，-> {merge（DealPrize.deletable）} ，: class_name =>  DealPrize 
  

...因此您可以：

  deleteable_deal_prizes.limit（prize_number_was-奖品编号）.delete_all 
  

When creating a model Deal, I use an after_create to create prizes on the DealPrize table.

Deal and DealPrize have a belong to/has_many relations: a Deal has many Deal prizes and a Dealprize belongs to a Deal.

It works like this: on my admin panel (using activeadmin), inside a Deal, I have a column 'prize-number' and I use an after_create so that every time the admin creates a new deal, the app takes this prize_number column, and create this volume of prizes (inserting as many rows as necessary=> often more than 300,000) inside the DealPrize table.

So I create a Deal, and automatically, the app creates a huge number of associated objects (prizes) say 300,000.

The problem is I might wish 2 days later to change the prize number from 300,000 to 272,000 for example (less prizes) or 324,000 (more prizes).

How can I update the created Deal and tell my Rails app to update the number of associated Prizes (removing some or adding some) without deleeting and recreating the whole Deal object ?

Also, I need a fast way (like the one I use to create the Deal => raw sql and transaction as the number of rows to create at once is very high).

modals Deals.rb

has_many   :deal_prizes,  dependent: :delete_all

after_create :create_deal_prizes

CONNECTION = ActiveRecord::Base.connection.raw_connection

    def create_deal_prizes
      begin 
        CONNECTION.describe_prepared('yokoatxz')
      rescue PG::InvalidSqlStatementName
        CONNECTION.prepare('yokoatxz', 'INSERT INTO deal_prizes (deal_id,created_at,updated_at,admin_user_id) values ($1, $2, $3, $4)') 
      end

      Deal.transaction do  
        self.prizes_number.times do |i| 
          CONNECTION.exec_prepared('yokoatxz',  [ { value: self.id},
                                                  { value: '2009-01-23 20:21:13' },
                                                  { value: '2009-01-23 20:21:13' },
                                                  { value: self.admin_user_id }
                                                ] )
        end
      end
    end

Thanks for your help, Mathieu

解决方案

Well I think that if you just wanted to change the number of deal_prizes then you could use a before_save callback on the Deal to test for a difference between prize_number and prize_number_was, and issue either an insert or delete statement appropriately.

I expect for the delete you'd do something like:

deal_prizes.limit(prize_number_was - prize_number).delete_all

... if you didn't care which were deleted.

You would probably want to use a scope on the deal_prizes:

def self.deletable
  where(:taken => false)
end

... to apply the condition by which rows can be deleted though, and then merge this into the association on deal ...

has_many :deletable_deal_prizes, -> {merge(DealPrize.deletable)}, :class_name => "DealPrize"

... so you can:

deleteable_deal_prizes.limit(prize_number_was - prize_number).delete_all

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