无法看到对值来自服务的变量的出价

Question

一开始，我使用了一个给我一个字符串的服务，我将它保存在变量中，并使用大括号将它显示在 HTML 上，但我没有看到该值，我已经测试了该服务，该值来自后端，所以我认为情况是由于生命周期造成的。 我尝试了ngOnInit和ngAfterViewInit ，但我无法获得该值。

elCodigoInterno: string;

  ngOnInit() {
    this.iniciarFormulario();   

    this.dataService.getCodigoInterno().subscribe(
      //result => this.colaborador.codigoInterno = result,
      result => this.elCodigoInterno = result,
      error => console.log('error ', error)
    );       
  }

  ngAfterViewInit(){
    this.dataService.getCodigoInterno().subscribe(
      //result => this.colaborador.codigoInterno = result,
      result => this.elCodigoInterno = result,
      error => console.log('error ', error)
    ); 
  }

<label for="codigoInterno">Código Interno </label>      
<p>{{elCodigoInterno}} </p>

Answer 1

如果在dataService中创建一个public变量，然后在getCodigoInterno方法中赋值给这个变量，就可以得到你想要得到的值。

我可以举个例子

///// 服务

export class LocationService {
  public locationlist: Location[] | any;
  public location: Location | any;
  constructor(private http: HttpClient) { }


  public getAllLocation(): Observable<Location[]> {
    return this.http.get<ApiResponse>(environment.locationApiUrl, {}).pipe(
      map(
        (response: ApiResponse) => {
          return this.locationlist = response.content;
        }
      )
    );
  }
}

///// 成分

 public location;
      constructor(private locationService: LocationService) { }
    
      ngOnInit(): void {
        this.location = this.locationService.locationlist[0].id;
      }
      public getAlllocations() {
      this.locationService.getAllLocation().subscribe(location => {
      ...
      });
   }