@Observed装饰数据model

@Observed
export class CartModel {
  id?:number
  goods_name?:string
  goods_code?:string
  goods_big_logo?:string
  goods_price?:number
  goods_count?:number
  goods_checked?:number
}

父页面使用反例，使用字面量赋值的方式，子组件修改数据，数据改变，页面不会变化

import { ProductItem } from '../view/ProductItem'
@Component
export struct Cart {
  @State carts: CartModel[] = [
	    {
	      "id": 4,
	      "goods_name": "创维（Skyworth）65M6E 65英寸 4K超高清智能酷开网络液晶电视",
	      "goods_big_logo": "https://inews.gtimg.com/news_bt/O7ZsQ9IrSfcWAWLPeaRcfeEt5FdyeTfnFYrSGmDSKlU0sAA/1000",
	      "goods_code": "57443",
	      "goods_price": 4999,
	      "goods_count": 1,
	      "goods_checked": 0
	    },
	]
 build() {
	List({ space: 10 }) {
              ForEach(this.carts, (item: CartModel, index: number) => {
                ListItem() {
                  ProductItem({ item: item,computedTotalPrice:this.computedTotalPrice })
                }
                
              }, (item: CartModel) => JSON.stringify(item.id))
            }
            .padding({ bottom: 10 })
	}
}

父页面使用正例 ，使用new class类的方式

import { ProductItem } from '../view/ProductItem'
@Component
export struct Cart {
  @State carts: CartModel[] = []
  aboutToAppear(): void {
	    const cart01 = new CartModel()
	    cart01.id = 1
	    cart01.goods_name = "创维（Skyworth）65M6E 65英寸 4K超高清智能酷开网络液晶电视"
	    cart01.goods_code = "57443"
	    cart01.goods_big_logo= "https://inews.gtimg.com/news_bt/O7ZsQ9IrSfcWAWLPeaRcfeEt5FdyeTfnFYrSGmDSKlU0sAA/1000"
	    cart01.goods_price = 4999
	    cart01.goods_count = 1
	    cart01.goods_checked = 0
	
	    this.carts.push(cart01)
	    const cart02 = new CartModel()
	    cart02.id = 2
	    cart02.goods_name = "创维（Skyworth）65M6E 65英寸 4K超高清智能酷开网络液晶电视"
	    cart02.goods_code = "57443"
	    cart02.goods_big_logo= "https://inews.gtimg.com/news_bt/O7ZsQ9IrSfcWAWLPeaRcfeEt5FdyeTfnFYrSGmDSKlU0sAA/1000"
	    cart02.goods_price = 1999
	    cart02.goods_count = 1
	    cart02.goods_checked = 0
	    this.carts.push(cart02)

  }
   build() {
		List({ space: 10 }) {
	       ForEach(this.carts, (item: CartModel, index: number) => {
	            ListItem() {
	              ProductItem({ item: item,computedTotalPrice:this.computedTotalPrice })
	            }
	       }, (item: CartModel) => JSON.stringify(item.id))
	    }
	}
}

子组件使用

import { CartModel } from '../viewmodel/CartModel'
@Component
export struct ProductItem {
  @ObjectLink item: CartModel
}

参考文档：@Observed装饰器和@ObjectLink装饰器：嵌套类对象属性变化