Rails4:无法修改冻结哈希

Question

该Order模型:

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

has_many Sales:

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

当我销毁一个Order,相关的Sales也应该被销毁,但是这样做时我遇到了一个错误:

RuntimeError in OrdersController#destroy
Can't modify frozen hash

这一行突出显示:self.price = mrr * self.quantity.to_f.

Sale手动逐步销毁所有关联的记录可以正常工作而不会出错.在没有Sale关联之后,我也可以破坏Order记录.

有任何想法吗？

Answer 1

在突出显示的行上,您应该确保sale在更新其price属性时不会销毁它:

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?