两种模型，一种 STI 和一种验证 [英] Two models, one STI and a Validation

问题描述

假设我有两个表——Products 和 Orders.为简单起见，假设一次只能购买一种产品，因此没有像 order_items 这样的连接表.所以关系是Product有很多个订单，Order属于product.因此，product_id 是 Order 表中的一个 fk.

Let's say I have two tables -- Products and Orders. For the sake of simplicity assume that only one product can be purchased at a time so there is no join table like order_items. So the relationship is that Product has many orders, and Order belongs to product. Therefore, product_id is a fk in the Order table.

产品表为 STI -- 子类为 A、B、C.

The product table is STI -- with the subclasses being A, B, C.

当用户订购子类产品 C 时，必须检查订单模型字段 order_details 和 order_status 上的两个特殊验证.对于所有其他产品子类(即 A 和 B)，这两个字段可以为零.换句话说，当用户购买 A 和 B 时，不需要对这两个字段运行验证.

When the user orders subclass Product C, two special validations must be checked on the Order model fields order_details and order_status. These two fields can be nil for all other Product subclasses (ie A and B). In other words, no validation needs to run for these two fields when a user purchases A and B.

我的问题是:

如何在 Order 模型中编写验证(可能是自定义的?)，以便 Order 模型知道只对 ITS 两个字段(order_details 和 order_status)运行验证，当将产品子类 C 的 fk_id 保存到订单表?

How do I write validations (perhaps custom?) in the Order model so that the Order model knows to only run the validations for ITS two fields -- order_details and order_status -- when the fk_id to Product subclass C is being saved to the orders table?

推荐答案

关键是在Order模型中添加一个validate方法来检查细节:

The key is to add a validate method in the Order model to check for specifics:

  def validate
    if product and product.type_c?
      errors.add(:order_details, "can't be blank") if order_details.blank?
      # any other validations
    end
  end

或者类似的东西.只需检查 validate 中的类型并添加适当的错误.我刚刚编写了 type_c? 函数.只需检查类型，但您的 Product 模型已定义.

Or something along those lines. Just check for the type in validate and add the appropriate errors. I just made up the type_c? function. Just check the type however your Product model is defined.

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