ruby-on-rails - Rails4 : Can't modify frozen hash

Question

Order模型:

class Order < ActiveRecord::Base
  has_many :sales, dependent: :destroy, inverse_of: :order
end

has_many Sale s:

class Sale < ActiveRecord::Base
  belongs_to :order, inverse_of: :sales
  validates :order, :product, :product_group, :presence => true
  before_create :price

  def price
    mrr = Warehouse.where(:product => self.product).pluck(:mrr).shift.strip.sub(',', '.').to_f
    self.price = mrr * self.quantity.to_f
  end
end

当我摧毁一个 Order ，关联 Sale s 也应该被销毁，但我在这样做时遇到了一个错误:

RuntimeError in OrdersController#destroy
Can't modify frozen hash

该行突出显示: self.price = mrr * self.quantity.to_f .

销毁所有关联的 Sale s 记录手动分步工作，没有错误。后无 Sale不再关联，我可以销毁 Order也记录。

有任何想法吗？

Answer 1

在突出显示的行上，您应该确保 sale更新其 price 时不会被破坏属性:

self.price = mrr * quantity.to_f unless destroyed? # notice, no need for self before quantity
# or
write_attribute(:price, mrr * quantity.to_f) unless destroyed?