HarmonyOS @ObjectLink到底怎么用

这个页面是数据是一个ClassA数组记作classA[]，ClassA里面又有一个ClassB数组，大概是下面这样的：

@Observed
export class ClassA {
  a: number;
  datas: ClassB[];
}

@Observed
export class ClassB {
  b: number;
  c: number;
}

@Entry
@Component
struct Index {
  @State pageDatas: ClassA[] = []

  build() {


    Tabs({ barPosition: BarPosition.Start, index: this.currentIndex, controller: this.controller }) {


      ForEach(this.pageDatas, (page_item: ClassA, page_index: number) => {


        TabContent() {
          PageView({
            page_item: page_item,
          })
        }

      }
    }

    @Component

    export struct PageView {
      @ObjectLink page_item: ClassA;

      build() {

        Column() {

          Text(this.page_item.a + "")
            .onClick((e: ClickEvent) => {

              弹出Dialog，
              选择a值
              this.page_item.a = selecta
            }

          ForEach(this.page_item.datas, (item: ClassB, index: number) => {

            ItemView({
              page_item: this.page_item
              item: item
            })

          }, (item: ClassB) => JSON.stringify(item))

        }

      }
    }

    @
    Component

    export struct ItemView {
      @ObjectLink page_item: ClassA;
      @ObjectLink item: ClassB;

      build() {
        Row() {


          Button("加1")
            .onClick((e: ClickEvent) => {
              this.item.b = this.item.b + 1
            }

          TextInput({ text: this.item.b === 0 ? '' : this.item.b.toString() })
            .onChange((value: string) => {
              if (value === null || value === undefined || value === '') {
                this.item.b = 0
              } else {
                this.item.b = parseInt(value);
              }
            }


          Text(this.page_item.a * item.b * item.c + "m³")
        }
      }
    }
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