HarmonyOS使用@Objectlink和 @watchs 如何只监听对象一个属性的变化

@Component 
export struct TestView{ 
  @ObjectLink @Watch("updateViewModel") viewModel:PlayFlowViewModel 
  updateViewModel(){ 
    console.log("TestView updateViewModel") 
  } 
} 
@Observer 
export class PlayFlowViewModel{ 
  playBaseData:PlayBaseData | null = null 
  option: Options = new Options() 
  datasource:DataSource = new DataSource() 
  playEvent:ReceiverEvent = {event:0,bundle:null} 
}