node.js - Angular : Receive responses in order with the calls

Question

嗨，我对 Angular 和 Observables 还很陌生

我正在尝试通过循环通过对象的 ID 获取对象。 但没有按顺序收到我的回复。

示例

get ID(1)
get ID(2)
get ID(3)
Receive Object ID(2)
Receive Object ID(3)
Receive Object ID(1)

是否可以让我的对象恢复正常？ 下面是我多次调用我的服务函数的地方:

conferences-attendance.component.ts

  ExportExcelAttendance() {
    for (var i = 0; i < this.contactsAttendance.length; i++) {
      this.practiceService.GetPracticebyDBID(this.contactsAttendance[i].practiceId)
        .subscribe(
        (practice: Practice) => {
          this.practicesAttendance.push(practice);
          if (this.practicesAttendance.length == this.contactsAttendance.length) {
            this.ExportExcelAttendance2();
          }
        },
        error => this.errorMessage = <any>error
        );
    }
  }

这是我的服务中的函数，我在其中接收数据(不按调用顺序)。

practices.service.ts

    GetPracticebyDBID(id: string) {
        let params: URLSearchParams = new URLSearchParams();
        params.set('thisId', id);
        let requestOptions = new RequestOptions();
        requestOptions.params = params;
        return this.http.get('http://ec2-34-231-196-71.compute-1.amazonaws.com/getpractice', requestOptions)
            .map((response: Response) => {
                return response.json().obj;
            })
            .catch((error: Response) => Observable.throw(error.json()));
    }

Answer 1

forkJoin 为您提供了更少的代码，

const arrayOfFetches = this.contactsAttendance
  .map(attendee => this.practiceService.GetPracticebyDBID(attendee.practiceId) );

Observable.forkJoin(...arrayOfFetches)
  .subscribe((practices: Practice[]) => {
      this.practicesAttendance = practices;
      this.ExportExcelAttendance2();
  });

编辑 折断! @Anas 打败了我。虽然，我认为你不需要 concatAll()