HarmonyOS @ObjectLink修饰的变量在父组件改变后，无法触发ui刷新？

Question

我在父组件中重新对@ObjectLink修饰的变量重新创建了一个对象，但在子组件中无法重新执行UI的刷新

Answer 1

可参考文档：

https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/arkts-observed-and-objectlink-V5\#%E5%B5%8C%E5%A5%97%E5%AF%B9%E8%B1%A1

@observed修饰的类相当于对原始类又封装了一次构造器，通过JSon转化出来的是原始构造，破坏了Observed修饰， 因此无法响应页面的生效。 数组类型的增减可以被UI框架观察到，但是数组内某一项的变量的值的修改不会被UI框架观察到。 class类型的变量，是可以直接被UI框架观察到，和数组类型一样，class类型的属性的变量的值改变同样不会被UI框架观察到

可以参考以下demo:

class BasicDataSource implements IDataSource {
  private listeners: DataChangeListener[] = [];
  private originDataArray: string[] = [];

  public totalCount(): number {
    return 0;
  }

  public getData(index: number): string {
    return this.originDataArray[index];
  }

  registerDataChangeListener(listener: DataChangeListener): void {
    if (this.listeners.indexOf(listener) < 0) {
      console.info('add listener');
      this.listeners.push(listener);
    }
  }

  unregisterDataChangeListener(listener: DataChangeListener): void {
    const pos = this.listeners.indexOf(listener);
    if (pos >= 0) {
      console.info('remove listener');
      this.listeners.splice(pos, 1);
    }
  }

  notifyDataReload(): void {
    this.listeners.forEach(listener => {
      listener.onDataReloaded();
    })
  }

  notifyDataAdd(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataAdd(index);
    })
  }

  notifyDataChange(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataChange(index);
    })
  }

  notifyDataDelete(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataDelete(index);
    })
  }

  notifyDataMove(from: number, to: number): void {
    this.listeners.forEach(listener => {
      listener.onDataMove(from, to);
    })
  }
}

class MyDataSource extends BasicDataSource {
  private dataArray: string[] = [];

  public totalCount(): number {
    return this.dataArray.length;
  }

  public getData(index: number): string {
    return this.dataArray[index];
  }

  public addData(index: number, data: string): void {
    this.dataArray.splice(index, 0, data);
    this.notifyDataAdd(index);
  }

  public pushData(data: string): void {
    this.dataArray.push(data);
    this.notifyDataAdd(this.dataArray.length - 1);
  }

  public deleteData(index: number): void {
    this.dataArray.splice(index, 1);
    this.notifyDataDelete(index);
  }
}

@Entry
@Component
struct MyComponent {
  private data: MyDataSource = new MyDataSource();

  aboutToAppear() {
    for (let i = 0; i <= 20; i++) {
      this.data.pushData(`Hello ${i}`)
    }
  }

  build() {
    List({ space: 3 }) {
      LazyForEach(this.data, (item: string, index: number) => {
        ListItem() {
          Row() {
            Text(item).fontSize(50)
              .onAppear(() => {
                console.info("appear:" + item)
              })
          }.margin({ left: 10, right: 10 })
        }
        .onClick(() => {
          // 点击删除子组件
          this.data.deleteData(index);
        })
      }, (item: string) => item)
    }.cachedCount(5)
  }
}