如果我了解您的需求，那么您想使用请求1中的数据发出请求2。

这可以通过RxJs switchMap运算符轻松完成。

您需要的只是

// First you pipe to the source observable which GETs the data you need
this.firstRequest$.pipe(
  // you may apply a filter() pipe which will pass data forth if it returns true
  // like filter(res => res.status === 'SUCCESS')

  // Then you call method which receives some needed data for second request
  // and returns observable of 2nd request
  switchMap(res => this.secondRequest(res.id))
).subscribe(res => {
  // process the result of 2nd request
});

这是一个小例子

https://stackblitz.com/edit/rxjs-47hmp1?devtoolsheight=60

import { of } from 'rxjs'; 
import { map,filter,switchMap } from 'rxjs/operators';

// Here we get a source observable
function getFirstObservable() {
  return of({
    data: {
      id: 3
    },status: 'SUCCESS',});
}

// This is a second source which requires some data to receive first
function getSecondObservable(id: number) {
  return of('I was called with id ' + id);
}

getFirstObservable().pipe(
  // filter allows emmited values to pass only when resolves to true
  filter(response => response.status === 'SUCCESS'),// Allows us to subsribe to the observabe returned by callback when
  // source observable emits value
  switchMap(response => getSecondObservable(response.data.id))
).subscribe(result => {
  console.log(result);
  // handle result

  // here goes the result of a second observable when and only when second observable
  // emmits value
},err => {
  // handle error logic
})

只有在第一个调用完成后才进行后续的依赖请求-使用http请求返回的Observable来执行此操作。这使您可以按所需顺序链接请求。

  loadData(): void {
    const matchID = +this.route.snapshot.paramMap.get('id');
    this.getMatchByUniqueID(matchID).subscribe(match => { //subscribe to the http observable
        if (match.status === 'SUCCESS') {
          this.match = Object.setPrototypeOf(match.data,Match.prototype);
        }
        this.match.playerIDs.forEach(id => {
        this.getPlayerByUniqueID(id); // get requests that can only work when the match object is set correctly
      });
  }

  // ---------------------------------------------------------
  // HTTP ----------------------------------------------------
  // ---------------------------------------------------------
  getMatchByUniqueID(id: number): Observable { // <-- note we are returning the observable here
    return this.matchService.getMatch(id);
  }

  getPlayerByUniqueID(id: number): void {
    this.playerService.getPlayer(id)
      .subscribe(player => {
        if (player.status === 'SUCCESS') {
          this.players.push(Object.setPrototypeOf(player.data,Player.prototype));
        }
      });
  }

您需要在match.component.ts中更改您的 loadData 和 getMatchByUniqueID 方法以获得正确的答案。从第一个api调用获取所有数据后，您应该调用 getPlayerByUniqueID 方法。

loadData(): void {
  const matchID = +this.route.snapshot.paramMap.get('id');
  this.getMatchByUniqueID(matchID);          
}

getMatchByUniqueID(id: number): void {
  this.matchService.getMatch(id)
    .subscribe(match => {
      if (match.status === 'SUCCESS') {
        this.match = Object.setPrototypeOf(match.data,Match.prototype);

        // call the playerByUniqueId from here
        this.match.playerIDs.forEach(id => {
          this.getPlayerByUniqueID(id);
        });
      }
    });
}