Angular2 ngModel在異步回調后未更新

Question

為什么angular2雙向數據綁定在這種情況下不起作用？

<span style="color:white">{{searchLocation}}</span>
<input  name="searchLocation" type="text" placeholder="Search" [(ngModel)]="searchLocation">
<button class="btn btn-outline-success" type="submit" (click)="search()">Search</button>

目標組件是HeaderComponent

export class HeaderComponent implements OnInit {

  searchLocation: string;
  @Output() locationFound: EventEmitter<Position> = new EventEmitter<Position>();

  constructor(private _locationService: LocationService) { }

  ngOnInit() {
     this.searchLocation ="";
  }

  search():void{

    this._locationService.geocodeAddress(this.searchLocation)
        .subscribe((position:Position)=>{
          this.searchLocation ="new value";
          this.locationFound.emit(position);
    });
  }
}

在訂閱塊之后，searchLocation會更改，但視圖不會更新。

我希望有人可以幫助我

Answer 1

      this.searchLocation ="";

searchLocation被指定為null。 如果存在null，則不會更新DOM。 嘗試給一些有效的字符串。