组合多个Observable

Question

我有这两个可观测量:

this.areasService.getSelectAreas({})
   .subscribe((result) => this.areasSelect = result.json().data.areas);
this.stationsService.getSelectStations({})
   .subscribe((result) => this.stationsSelect = result.json().data.stations);

填充这两个变量(异步)this.areasSelect&this.stationsSelect.

我还有一个第三个observable,我需要继续这些值:

this.transportsService.getTransport().subscribe((res) => {
     console.log(this.areasSelect)
     console.log(this.stationsSelect)
})

我如何组合这3个可观察量？

Answer 1

你可以使用forkJoin：

import { forkJoin } from 'rxjs/observable/forkJoin';

let areaSelect$ = this.areasService.getSelectAreas({})
.map(res => res.json().data.areas)
.do(val => this.areaSelect = val);

let stationSelect$ = this.stationsService.getSelectStations({})
.map(res => res.json().data.stations)
.do(val => this.stationSelect = val);

forkJoin(areaSelect$,stationSelect$)
.mergeMap(data=>{
   //data is an array with 2 positions which contain the results of the 2 requests. data[0] is the vale of this.areaSelect for example
   return this.transportsService.getTransport(data[0],data[1]);
}).subscrite(res => {
  // res is the response value of getTransport
})