Rails 嵌套事务

Question

我正在尝试制作 rails 应用程序，但我遇到了这个问题。我有嵌套事务，虽然它们一直在工作。但是，我发现它们不能正常工作。

这是用户服务

    class UserService
    def self.reduce_balance!(user, delta, attachmentable)
      ActiveRecord::Base.transaction do
        user.balance.amount -= delta
        balance_decrease = BalanceDecrease.new(user: user, attachmentable: attachmentable, balance_before: user.balance.amount_was, amount: delta)
        user.balance.save!
        balance_decrease.save!
      end
      return true
    end
    end

有游戏服务

    class GameService
      def self.take_spot(user, spot)
        if UserService.have_enough_money? user, game.spot_price
          begin
            ActiveRecord::Base.transaction do
              spot.free = false
              spot.user = user
              spot.save!
              UserService.reduce_balance!(user, game.spot_price, spot)
              return res = {success: true, json: spot, status: 200}
            end
          rescue => e
            return res = {json: {error: 1, error_message: "Something gone wrong"}, status: 500}
          end
        else
          return res = {json: {error: 1, error_message: "You don't have enough money"}, status: 400}
        end
      end
    end

我的控制器是

    def update
      @res = GameService.take_spot current_user, @spot
      return render json: @res[:json], status: @res[:status] unless @res[:success]
    end

1700 条查询中有 1 条以某种方式出错：现货已被购买，余额未减少。 This is picture of json

json文件（下图）：

{
"id": 1759,
"type": "BalanceDecrease",
"balance_before": "950.00",
"amount": "10.00",
"spot": {
"id": 1965,
"number": 7,
"free": false,
"game": {
"id": 19,
"name": "M249 | Блокировка",
"img_url": "(img url)",
"stattrak": false,
"spot_price": "10.00",
"state": "ended",
"created_at": "2015-11-26T23:20:28.081+03:00",
"updated_at": "2015-11-26T23:20:59.406+03:00"
},
"created_at": "2015-11-26T23:20:28.087+03:00",
"updated_at": "2015-11-26T23:20:57.270+03:00"
}
},
{
"id": 1758,
"type": "BalanceDecrease",
"balance_before": "950.00",
"amount": "10.00",
"spot": {
"id": 1964,
"number": 6,
"free": false,
"game": {
"id": 19,
"name": "M249 | Блокировка",
"img_url": "(img url)",
"stattrak": false,
"spot_price": "10.00",
"state": "ended",
"created_at": "2015-11-26T23:20:28.081+03:00",
"updated_at": "2015-11-26T23:20:59.406+03:00"
},
"created_at": "2015-11-26T23:20:28.087+03:00",
"updated_at": "2015-11-26T23:20:57.282+03:00"
}
}

我有 10 美元的 DigitalOcean 水滴。会不会是问题所在？

Answer 1

ActiveRecord::Rollback 不会传播到包含事务块之外，因此父事务不会收到嵌套在子事务中的异常。

为确保父事务收到回滚，您必须向子事务添加 requires_new: true 选项。

查看 this article and docs 了解更多详情。

所以将它应用到你的案例中，你应该user_service.rb如下：

class UserService
  def self.reduce_balance!(user, delta, attachmentable)
    ActiveRecord::Base.transaction(requires_new: true) do
      # code omitted
    end
  end
end

Answer 2

您的问题源于您使用交易的方式。

无论何时嵌套它们，都必须使用 requires_new: true

ActiveRecord::Base.transaction do 
  ActiveRecord::Base.transaction(requires_new: true) do 

  end
end

解释得很好in the doc。

顺便说一句，总是使用 requires_new: true.

也没什么坏处

旁注，您似乎使用服务对象并将它们链接起来，也许 this would interest you。

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