作为 Subject 传递和解包 Observable

Question

我需要将数据从一个组件传递到另一个组件，但我很难做到。

我有一个 Observable 需要作为 Subject 传递，这是另一个 Observable。我怎么做？我目前使用的方式在 目标组件 undefined.

中不起作用

这是我的：

card.component.ts （一切开始的地方）

showBox(studentID) {
    const airportPickup = this.studentService.getCurrentStudents().pipe(
        map(snaps => {
            const student = snaps.find( s => s.studentID === studentID );
            return {
                requirePickup: student.pickup,
                whopickup: student.whoPickup
            };
        })
    );
    this.studentService.airportPickupDropoff.next(airportPickup);
}

如果我 console.log() airportPickup 我得到了对象。没有问题。问题是当我在其他组件中获取它时，我将其作为 undefined.

flight-info.component.ts (目标)

getAirportPickup() {
    this.studentService.airportPickupDropoff.subscribe(
        (apdata) => {
            this.airportPickupDropoff = apdata;
        },
        (e) => alert(e)
    );
}

服务我有这个：

airportPickupDropoff = new Subject<any>();

Answer 1

您需要订阅可观察对象，或将其与 RxJS 运算符（例如 tap）链接起来，以便将可观察对象的值分配给您的 airportPickupDropoff 主题。

选项 1：

showBox(studentID) {
  this.studentService.getCurrentStudents().pipe(
    map(snaps => {
      const student = snaps.find( s => s.studentID === studentID );
      return {
        requirePickup: student.pickup,
        whopickup: student.whoPickup
      };
    }),
  ).subscribe(response => {
    this.studentService.airportPickupDropoff.next(response);
  });
}

选项 2：

showBox(studentID) {
  this.studentService.getCurrentStudents().pipe(
    map(snaps => {
      const student = snaps.find( s => s.studentID === studentID );
      return {
        requirePickup: student.pickup,
        whopickup: student.whoPickup
      };
    }),
    tap(response => this.studentService.airportPickupDropoff.next(response)),
  ).subscribe();
}

Answer 2

也许通过 Subject 而不是另一个 Observable 发送数据会更好？

showBox(studentID) {
  ///...
  airportPickup.subscribe(apdata => this.studentService.airportPickupDropoff.next(apdata));
}

作为 Subject 传递和解包 Observable

Passing and unwrapping Observable as Subject

rxjs

angular2-observables

angular

rxjs-observables