I get a RxJS Observable from an httpService which is the actual http from Angular. Now as soon as I get a postive result from that, I want to process the next http Request which I get from this.retrieve(). This is more or less concattening requests. Is there a better way of doing it?
return this.httpService.query(data)
.map(data => {
if(data.status > 1)
this.retrieve().subscribe();
return data;
});
Chaining HTTP requests can be done using flatMap or switchMap operators. Say we want to make three requests where each request depends on the result of previous one:
this.service.firstMethod()
.flatMap(firstMethodResult => this.service.secondMethod(firstMethodResult))
.flatMap(secondMethodResult => this.service.thirdMethod(secondMethodResult))
.subscribe(thirdMethodResult => {
console.log(thirdMethodResult);
});
This way you can chain as much interdependent requests you want.
UPDATE: As of RxJS version 5.5 pipeable operators were introduced and the syntax has slightly changed:
import {switchMap, flatMap} from 'rxjs/operators';
this.service
.firstMethod()
.pipe(
switchMap(firstMethodResult => this.service.secondMethod(firstMethodResult)),
switchMap(secondMethodResult => this.service.thirdMethod(secondMethodResult))
)
.subscribe(thirdMethodResult => {
console.log(thirdMethodResult);
});