Rails after_initialize 仅适用于“new" [英] Rails after_initialize only on "new"

问题描述

我有以下两种型号

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运动，所以在我的 sports_controller.rb 中我有:

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 将产品的创建移动到运动模型:

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，只要实例化模型(即从 find 调用中)，就会调用 after_initialize.所以这不是我想要的行为.

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.

我应该如何建模所有 sport 都有一个 product 的需求?

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

谢谢

推荐答案

如您所说，将逻辑放在控制器中可能是最好的答案，但是您可以通过执行以下操作来使 after_initialize 工作以下:

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，只有在没有产品存在时才设置产品.与控制器中的逻辑相比，它可能不值得开销和/或不那么清晰.

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.

根据 Ryan 的回答，在性能方面，以下可能会更好:

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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