等待构造函数完成初始化

Question

我有下面的代码来调用我的应用程序中的api服务。问题是，当我调用apiPost()函数时，this.apiToken值是空的。这是因为当我调用apiPost()时，构造函数还没有初始化，apiToken值还没有赋值。

this.storageService.get(constant.storage_key.api_token).then((data) => {
      this.apiToken = data;
     //Is it possible to return Observable inside here?
});

如何等待获取到apiToken后再调用this.httpAng.post()

export class MyApiService {

  apiToken = "";

  constructor(
    private httpAng: HttpClient,
    private storageService: StorageService,
  ) {
    this.storageService.get(constant.storage_key.api_token).then((data) => {
      this.apiToken = data;
    });
  }

 
  apiPost(aUrl, aParams): Observable<any> {
    let httpOptions: any = {
      headers: new HttpHeaders({
        'Content-Type': 'application/json',
        'Authorization': 'Bearer ' + this.apiToken,
      }),
    }

    return new Observable((observer) => {
      // Post
      this.httpAng.post(aUrl, aParams, httpOptions).subscribe(
        async (data) => {
          switch (data['status']) {
            case 0:
              observer.next(data);
              break;
            default:
              this.alert.alertMessage(
                data['message']
                , () => {
                  observer.error(data)
                }
              )
              observer.error(data);
          }
        },
        async (error) => {
          console.log(error)
          observer.error(error);
        }
      );
    });
  }
}

Answer 1

Angular observable return undefined results

根据上面的帖子更改了我的代码，并使用了来自rxjs和switchMap的from。