使用活动模型序列化器的嵌套多态关联

Question

我刚刚开始研究在rails中进行序列化，并且在将其设置为嵌套多态关联时遇到问题。

在我的购物Rails API中，我具有以下关联：

### Cart model
class Cart < ApplicationRecord
  has_many :discounts
end

### Discount model
class Discount < ApplicationRecord
  belongs_to :cart
  belongs_to :discountable, polymorphic: true
end

### Extras model (extra meaning you get 3 items for price of 2)
class Extra < ApplicationRecord
  has_many :discounts, as: :discountable
end

我使用序列化程序实现的是：

### Cart serializer
class CartSerializer < ActiveModel::Serializer
  has_many :discounts
end

### Discount serializer
class DiscountSerializer < ActiveModel::Serializer
  attribute :discountable, polymorphic: true
end

这反过来给了我这个json：

{
    "discounts": [
        {
            "discountable": {
                "id": 1,
                "kind": "extra",
                "name": "Grill Set",
                "product_ids": [
                    1,
                    2,
                    3
                ],
                "count": 2,
                "created_at": "2019-05-11T17:09:44.366Z",
                "updated_at": "2019-05-11T17:09:44.366Z"
            }
        }
    ]
}

但是我对此不太满意-我想省略created_at和updated_at属性，并将折扣一一列出（没有可打折嵌套）。

类似这样的东西：

{
    "discounts": [
        {
            "id": 1,
            "kind": "extra",
            "name": "Grill Set",
            "product_ids": [
                1,
                2,
                3
            ],
            "count": 2,
        }
    ]
}

很高兴获得帮助。