Rails after_initialize仅在"new"消息上初始化. [英] Rails after_initialize only on "new"

问题描述

我有以下2种型号

class Sport < ActiveRecord::Base
  has_many :charts, order: "sortWeight ASC"
  has_one :product, :as => :productable
  accepts_nested_attributes_for :product, :allow_destroy => true
end

class Product < ActiveRecord::Base
  belongs_to :category
  belongs_to :productable, :polymorphic => true
end

没有产品就不可能存在一项运动，因此在我的sports_controller.rb中我拥有:

A sport can't exist without the product, so in my sports_controller.rb I had:

def new
  @sport = Sport.new
  @sport.product = Product.new
...
end

我尝试使用after_initialize将产品的创建移至运动模型:

I tried to move the creation of the product to the sport model, using after_initialize:

after_initialize :create_product

def create_product
 self.product = Product.new
end

我很快了解到，每当实例化模型时(即从find调用)就会调用after_initialize.所以那不是我想要的行为.

I quickly learned that after_initialize is called whenever a model is instantiated (i.e., from a find call). So that wasn't the behavior I was looking for.

我应该如何对所有sport都具有product的需求进行建模?

Whats the way I should be modeling the requirement that all sport have a product?

谢谢

推荐答案

将逻辑放入控制器中可能是最佳答案，但是您可以通过执行以下操作使after_initialize起作用:

Putting the logic in the controller could be the best answer as you stated, but you could get the after_initialize to work by doing the following:

after_initialize :add_product

def add_product
  self.product ||= Product.new
end

这样，仅当不存在产品时才设置产品.与在控制器中包含逻辑相比，这可能不值得花费开销和/或不够清晰.

That way, it only sets product if no product exists. It may not be worth the overhead and/or be less clear than having the logic in the controller.

编辑:根据Ryan的回答，从性能角度考虑，以下方法可能会更好:

Per Ryan's answer, performance-wise the following would likely be better:

after_initialize :add_product

def add_product
  self.product ||= Product.new if self.new_record?
end

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