鸿蒙列表，item组件封装传参问题？@ObjectLink 和@Observerd

鸿蒙列表渲染，封装内容组件，进行item传参会报错？


class FoodClass {
  order_id: number = 0
  food_name:  string = ""
  food_price: number = 0
  food_count: number = 0
}

@Entry
@Component
struct Demo07 {
  @State message: string = 'Hello World'
  @State cartList: FoodClass[] = [{
    order_id: 1,
    food_name: '鱼香肉丝',
    food_price: 18.8,
    food_count: 1
  },{
    order_id: 2,
    food_name: '粗溜丸子',
    food_price: 26,
    food_count: 2
  },{
    order_id: 3,
    food_name: '杂粮煎饼',
    food_price: 12,
    food_count: 1
  }]
  build() {
    Row() {
      Column({space:20}) {
        ForEach(this.cartList,(item:FoodClass)=>{
          FoodItem({ item: $item })
        })
      }
      .width('100%')
    }
    .height('100%')
  }
}


@Component
struct FoodItem {
  @link item:FoodClass
  build() {
    Row(){
      Text(this.item.food_name)
      Text(`价格：${this.item.food_price}`)
      Text(`数量：${this.item.food_count}`)
    }.width('100%').justifyContent(FlexAlign.SpaceAround)
  }
}

报错：在这里插入图片描述
ArtTS不支持这么做，也就是Link修饰的数据必须得是最外层的 State数据，想要实现我们刚刚的设想，我们还得另辟蹊径。-后续ObjectLink 和Observerd会解决这个问题

解决方案：需要使用arkts官方提供的@ObjectLink 和@Observerd 以及 next版本规范的定义对象的interface解决
当然，如果只是对item内容进行纯ui渲染，可以不使用装饰器修饰，直接进行数据传递和接受渲染即可

import { goodsModel } from './Demo05'
@Entry
@Component
struct Demo07 {
  @State message: string = 'Hello World'
  @State cartList: FoodClass[] = [new FoodClassModel({
    order_id: 1,
    food_name: '鱼香肉丝',
    food_price: 18.8,
    food_count: 1
  }), new FoodClassModel({
    order_id: 2,
    food_name: '粗溜丸子',
    food_price: 26,
    food_count: 2
  }), new FoodClassModel({
    order_id: 3,
    food_name: '杂粮煎饼',
    food_price: 12,
    food_count: 1
  })]

  show(){
    return this.cartList.reduce((n,m)=>{
      return n+m.food_count
    },0)
  }

  build() {
    Row() {
      Column({ space: 20 }) {
        ForEach(this.cartList, (item: FoodClassModel) => {
          FoodItem({ item:item,carList:$cartList })
        })

        Text(this.show()+'')
      }
      .width('100%')
    }
    .height('100%')
  }
}


@Component
struct FoodItem {
  @ObjectLink item: FoodClassModel
  @Link carList:FoodClassModel[]
  build() {
    Row() {
      Text(this.item.food_name)
      Text(`价格：${this.item.food_price}`)
      Text(`数量：${this.item.food_count}`).onClick(()=>{
        this.carList = this.carList.map((aa:FoodClassModel)=>{
          if(aa.order_id===this.item.order_id){
             aa.food_count++
          }
          return aa
        })
      })
    }.width('100%').justifyContent(FlexAlign.SpaceAround)
  }
}


interface FoodClass {
  order_id: number
  food_name: string
  food_price: number
  food_count: number
}

@Observed
export class FoodClassModel implements FoodClass {
  order_id: number = 0
  food_name: string = ''
  food_price: number = 0
  food_count: number = 0

  constructor(model: FoodClass) {
    this.order_id = model.order_id
    this.food_name = model.food_name
    this.food_price = model.food_price
    this.food_count = model.food_count
  }
}

案例中：父组件的总和，是需要再传一个list数据进去，在子组件中使用@link 进行数据双向更新，才能实现ui试图更新的，因为鸿蒙数据只支持单层数据响应式更新。