在相关模型中的属性更改后运行before_save

Guido 发表于 Dev

圭多

我今天遇到了一些麻烦，无法思考如何解决这个问题。

基本上，我有一个名为Airplane的模型，它有很多付款。每笔付款可以分为许多期。行！

这是信息：

Model Airplane
- has_many payments
- before_save :checks_if_everything_has_been_paid

Model Payment
- belongs_to airplane
- has_many installments

Model Installment
- belongs_to payment

所以，我想做的是当分期付款的总和等于或大于飞机票的价值时，Airplane.paid将为true。我这样做是使用before_save“ checks_if_everything_has_been_paid。但这仅在“飞机”字段发生更改时才有效。

当“付款”和“分期付款”字段都发生更改时，如何运行此类？

我想检查每次更改分期付款或付款本身是否完成付款。

谢谢！

注入

代替after save在Airplane模型上定义after_add回调，而在payments关联上定义回调。

class Airplane < ActiveRecord::Base
  has_many :payments, after_add: :checks_if_everything_has_been_paid

  def checks_if_everything_has_been_paid
    # work some magic
  end
end

更新：如果我正确理解您的数据模型，我认为以下方法可能是更好的方法。如果保存了付款或分期付款，它将触发飞机检查全额付款：

class Airplane < ActiveRecord::Base
  has_many :payments
  has_many :installments, through: :payments

  def check_for_full_payment
    # work some magic
  end
end

class Payment < ActiveRecord::Base
  belongs_to :airplane
  has_many :installments

  after_save :trigger_full_payment_check

  def trigger_payments_check
    airplane.check_for_full_payment
  end
end

class Installment < ActiveRecord::Base
  belongs_to :payment

  delegate :airplane, to: :payment

  after_save :trigger_full_payment_check

  def trigger_payments_check
    airplane.check_for_full_payment
  end
end

这种方法的好处是，付款和分期付款中的逻辑相同，因此您可以将其提取到模块中：

module TriggerFullPaymentCheck
  def self.included(base)
    base.after_save :trigger_full_payment_check
  end

  def trigger_payments_check
    airplane.check_for_full_payment
  end
end

class Airplane < ActiveRecord::Base
  has_many :payments
  has_many :installments, through: :payments

  def check_for_full_payment
    # work some magic
  end
end

class Payment < ActiveRecord::Base
  include TriggerFullPaymentCheck

  belongs_to :airplane
  has_many :installments
end

class Installment < ActiveRecord::Base
  include TriggerFullPaymentCheck

  belongs_to :payment
  delegate :airplane, to: :payment
end