HarmonyOS @Prop同步给子组件的数据如何通过@Builder传递？

Question

以下demo代码中，在父组件中调用TestBuilder，传递一个string类型数据，通过TestBuilder再传递给TestComp，并更新TestComp中的UI，但实际无法刷新UI。请问中间有个builder透传的场景，如何传递数据并更新UI？

@Component
struct TestComp {
  @Prop text: string = "init"
  build() {
    Text(this.text)

  }
}

@Builder
function TestBuilder(text: string) {
  Column() {
    TestComp({ text: text })
  }
}

@Entry
@Component
struct BuilderUpdateData {
  @State message: string = 'Hello World';

  build() {
    Column() {
      TestBuilder(this.message)
      // TestComp({ text: this.message })  // 如果父组件直接调TestComp就可以刷新UI
      Button('update message', { stateEffect: true, type: ButtonType.Capsule })
        .width('80%')
        .height(40)
        .margin(10)
        .onClick(() => {
          this.message = "aaa"
        })

    }
    .height('100%')
    .width('100%')
  }
}

Answer 1

需按引用传递参数，参考文档：https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/arkts-builder-V5\#按引用传递参数

示例：

class Tmp {
  para: string = ""
}

@Component
struct TestComp {
  @Prop text: string = "1";
  build() {
    Text(this.text)
  }
}

@Builder
function TestBuilder($$ : Tmp) {
  Column() {
    TestComp({text: $$.para})
  }
}

@Entry
@Component
struct BuilderUpdateData {
  @State message: string = 'Hello World';

  build() {
    Column() {
      TestBuilder({para: this.message})
      // TestComp({ text: this.message }) // 如果父组件直接调TestComp就可以刷新UI
      Button('update message', { stateEffect: true, type: ButtonType.Capsule })
        .width('80%')
        .height(40)
        .margin(10)
        .onClick(() => {
          this.message = "aaa"
        })

    }
    .height('100%')
    .width('100%')
  }
}