HarmonyOS 关于对象数组内容变更不会引起UI刷新？

Question

参考API的链接：https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/arkts-observed-and-objectlink-V5

其中this.arrA[Math.floor(this.arrA.length/2)].c，@State无法观察到第二层的变化，但是ClassA被@Observed装饰，ClassA的属性的变化将被@ObjectLink观察到。

@Observed
export class FilterMaterialModel {
  cover: string
  id: string
  describe: string | null
  title: string
  fileAddress: string
  filterLocalPath: string
  downloadProgress: number

  constructor(
    cover: string,
    id: string,
    describe: string | null,
    title: string,
    fileAddress: string
  ) {
    this.cover = cover
    this.id = id
    this.describe = describe
    this.title = title
    this.fileAddress = fileAddress
    this.filterLocalPath = ''
    this.downloadProgress = 0
  }
}

List({ space: CommonConstants.MARGIN_16_PX }) {
  ForEach(this.curMaterialList, (material: FilterMaterialModel, index) => {
    ListItem() {
      FilterItemComponent({ material: material, isSelected: this.curMaterialIndex === index })
        .onClick(() => {
          this.curMaterialIndex = index
          this.lastCurMaterialIndex = index
          this.lastCurGroupIndex = this.curGroupIndex
          this.isSelectedFilter = true
          //如果此滤镜没有下载，则进行下载
          if (!material.filterLocalPath || material.filterLocalPath.length === 0) {
            this.downloadFilter(material, index)
          }
        })
    }
  }, (material: FilterMaterialModel) => material.id)
}
.width(CommonConstants.FULL_SIZE)
.height(CommonConstants.MARGIN_64_PX)
.scrollBar(BarState.Off)
.listDirection(Axis.Horizontal)
.alignListItem(ListItemAlign.Center)

@Component
struct FilterItemComponent {
  @ObjectLink material: FilterMaterialModel
  ...

  build() {
    Column() {
      Stack({ alignContent: Alignment.Center }) {
        Image(this.material.cover)
          .size({ width: CommonConstants.IMAGE_SIZE_44, height: CommonConstants.IMAGE_SIZE_44 })
          .borderRadius(4)

        if (this.material.downloadProgress > 0 && !this.material.filterLocalPath) {
          Progress({
            value: this.material.downloadProgress,
            total: 100,
            type: ProgressType.Ring
          })
            .color($r('app.color.white'))
            .backgroundColor($r('app.color.white_70'))
            .style({
              strokeWidth: 1.5
            })//.size({width: CommonConstants.IMAGE_SIZE_16, height: CommonConstants.IMAGE_SIZE_16})
            .size({ width: CommonConstants.IMAGE_SIZE_32, height: CommonConstants.IMAGE_SIZE_32 })
        } else if (!this.material.filterLocalPath || this.material.filterLocalPath.length === 0) {
          //如果此滤镜未下载
          Image($r('[HohemBaseLib].media.ic_download_16'))
            .size({ width: CommonConstants.IMAGE_SIZE_16, height: CommonConstants.IMAGE_SIZE_16 })
        }

        Text(`${this.material.downloadProgress ?? 0}`)
          .fontSize(CommonConstants.FONT_TIPS_12)
          .fontColor($r('app.color.highlight_deep'))
          .width(CommonConstants.IMAGE_SIZE_44)
          .textAlign(TextAlign.Center)
          .maxLines(1)
          .textOverflow({ overflow: TextOverflow.Ellipsis })
      }
      .size({ width: CommonConstants.IMAGE_SIZE_44, height: CommonConstants.IMAGE_SIZE_44 })
      .borderRadius(4)
      .borderWidth(this.getBorderWidth())
      .borderColor(this.getBorderColor())
      .rotate({ angle: ScreenOrientationUtil.getInstance().getRotateAngle(this.screenRotationStatus) }
    }
  }
}

当变更对象数组数据时无法变更UI。

this.curMaterialList[0].downloadProgress = 100
this.curMaterialList[0].filterLocalPath ='xxxxx'

其中filterLocalPath和downloadProgress是在网络请求中不存在的字段，为了符合需求，新增的为何使用Observe和ObjectLink不能引起UI刷新。

Answer 1

@Observed装饰器和@ObjectLink装饰器：嵌套类对象属性变化失效的主要原因有：

1、@Observed装饰器可以观察到嵌套对象的属性变化，其他装饰器仅能观察到第二层的变化。

2、需要将具有观测能力的类对象绑定组件，来确保当改变这些类对象的内容时，UI能够正常的刷新(New一个继承了Array的对象而不是自定义数组)，可以参考文档：https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/arkts-observed-and-objectlink-V5

状态管理使用文档：

https://gitee.com/openharmony/docs/blob/master/zh-cn/application-dev/quick-start/properly-use-state-management-to-develope.md\#%E5%B0%86%E7%AE%80%E5%8D%95%E5%B1%9E%E6%80%A7%E6%95%B0%E7%BB%84%E5%90%88%E5%B9%B6%E6%88%90%E5%AF%B9%E8%B1%A1%E6%95%B0%E7%BB%84

参考示例如下：

@Observed
export class ControlList extends Array<Controls> {
  constructor() {
    super();
  }
}

@Observed
export class Controls {
  uuid: string
  control_type: string
  control_weights: string
  control_name: string
  control_status: string
  control_location: string
  control_menu_levels: string
  control_position: string
  control_h_name: string
  control_value: string
  isSelect: boolean

  constructor(param: Controls) {
    this.uuid = param.uuid
    this.control_type = param.control_type
    this.control_weights = param.control_weights
    this.control_name = param.control_name
    this.control_status = param.control_status
    this.control_location = param.control_location
    this.control_menu_levels = param.control_menu_levels
    this.control_position = param.control_position
    this.control_h_name = param.control_h_name
    this.control_value = param.control_value
    this.isSelect = param.isSelect
  }
}

@Component
export struct TestPage {
  @ObjectLink dataSource: ControlList

  build() {
    Column() {
      List({ space: 10 }) {
        ForEach(this.dataSource, (item: Controls, index) => {
          ListItem() {
            ControlItem({
              item: item,
              dataSource: this.dataSource,
            })
          }
        }, (item: Controls) => JSON.stringify(item.uuid))
      }.margin({ top: 10, bottom: 10 })
    }
  }
}

@Component
struct ControlItem {
  @ObjectLink item: Controls
  @Link dataSource: ControlList

  build() {
    Row() {
      if (this.item.isSelect) {
        Row() {
          Text(this.item.control_h_name).fontSize(15).fontColor('#B11F1A')
          Image($r('app.media.startIcon')).width(20).height(20)
        }
        .width('100%')
        .borderRadius(18)
        .borderWidth(1)
        .borderColor('#FFAE2921')
        .padding(5)
        .justifyContent(FlexAlign.SpaceBetween)
      } else {
        Row() {
          Text(this.item.control_h_name).fontSize(15).fontColor('#525252')
        }
        .width('100%')
        .borderRadius(18)
        .borderWidth(1)
        .borderColor('#FFE3E4E4')
        .padding(5)
      }
    }.onClick(() => {
      this.item.isSelect = !this.item.isSelect
      this.dataSource.splice(0, 1);
      console.log('isSelect', JSON.stringify(this.item));
    })

  }
}

@Entry
@Component
struct Page {
  @State dataSource: ControlList = new ControlList()

  aboutToAppear(): void {
    let json =
      `{"uuid":"13","control_type":"1","control_weights":"0.400000","control_name":"起投金额","control_value":"buyerSmallestAmountQuery","control_h_name":"10万(含)-20万","control_h_value":"7;","control_status":"1","control_location":"transferList","control_menu_levels":"1","control_position":"second","isSelect":true}`
    let item: Controls = JSON.parse(json)
    for (let i = 1; i < 6; i++) {
      this.dataSource.push(new Controls(item));
    }
  }

  build() {
    Column() {
      TestPage({ dataSource: this.dataSource })
    }
  }
}