rails 为实例分配属性

Question

我正在计算我的交易总成本是多少。为了测试我是运行 Transaction.last.calculate_total_payment，它返回一个 BigDecimal，这是我想要的，但是 none 之后的实例正在更新属性。我做错了什么？

class Transaction < ActiveRecord::Base
    has_one :auction
    has_one :bid
    belongs_to :inventory_part      
    TIER0 = 0
    TIER1 = 5_000
    TIER2 = 50_000
    TIER3 = 500_000
    TIER4 = 1_000_000
.
.
.
.

    def calculate_total_payment
    part = self.bid.part_price

    self.tax = part * self.tax_rate

    if self.bid.tx.shipping_account
        self.final_shipping_cost = 0 
    else # testing purposes
        self.final_shipping_cost = self.bid.est_shipping_cost
    end
    price_before_fees = part + self.tax + self.final_shipping_cost

    if price_before_fees < TIER1 #5,000
      self.bid_aero_fee = price_before_fees * 0.025
      self.armor_fee = price_before_fees * 0.015
    elsif price_before_fees < TIER2 #50,000
      self.bid_aero_fee = (price_before_fees - TIER1) * 0.015 + 125
      self.armor_fee = (price_before_fees - TIER1) * 0.01 + 75
    elsif price_before_fees < TIER3 #500,000
      self.bid_aero_fee = (price_before_fees - TIER2) * 0.0125 + 800
      self.armor_fee = (price_before_fees - TIER2) * 0.0075 + 525
    elsif price_before_fees < TIER4 #1,000,000
      self.bid_aero_fee = (price_before_fees - TIER3) * 0.0075 + 6425
      self.armor_fee = (price_before_fees - TIER3) * 0.005 + 3900
    else # anything over a million
        self.bid_aero_fee = (price_before_fees - TIER4) * 0.0075 + 10175
        self.armor_fee = (price_before_fees - TIER4) * 0.0035 + 6400
    end

    self.total_fee = self.armor_fee + self.bid_aero_fee
    self.total_amount = price_before_fees + self.total_fee
  end
end

Answer 1

您永远不会在 calculate_total_payment 方法中调用 save。您需要显式保存对象才能将其持久保存在数据库中。

Answer 2

如果您想让您的更改持久保存在数据库中，您应该在最后调用 save!。如果没有这个，它将修改对象（因此更改将在重新加载或再次获取对象后消失）。

rails 为实例分配属性

rails assign attributes to instance

ruby-on-rails

instance

assign