仅在异步功能执行后执行功能

Question

我希望F1（）等待F2（）完全执行并获得rest调用响应并设置一些数据。

我尝试使用此代码

this.F1().subscribe(result => {
  this.F2(result);
})


    F1() {


      return this.graphDataService.getAvailableSpan(a, b).subscribe(res => {
        this.c = new Date(res.lastAvailableDate);
        return 1;
      }, error => {
        this.lastAvailableDate = new Date();
        return 1;
      })
    }

Answer 1

检查此 How can I call multiple API's on a function with Angular?

async apicall(){

      let data1 = await f1(); //your first function should return promises
      let data2 = await f2(); //your second function should return promises

    }

Answer 2

您可以这样做：

async getAsyncCall() {
        this.result = await this.httpclient.get(this.URL).toPromise();
        this.F2(result);
    }

Answer 3

您可以使用RxJS运算符使流异步。尝试以下

ngOnInit() {
  this.F1().subscribe(result => {
    this.F2(result);
  });
}

F1(): Observable<any> {
  return this.graphDataService.getAvailableSpan(a, b).pipe(
    tap((res) => {
      this.c = new Date(res.lastAvailableDate);
    }),
    catchError((error) => {          // <-- `catchError` should return an obervable
      this.lastAvailableDate = new Date();
      return of(error);
    })
  );
}