Question:

How can I combine multiple HTTP calls in Angular using RxJS?

Problem

I'm trying to make multiple HTTP calls simultaneously in my Angular service and I want to combine the responses into a single object. How can I do this using RxJS?

import { Injectable } from '@angular/core';

import { HttpClient } from '@angular/common/http';

import { Observable } from 'rxjs';

@Injectable({

providedIn: 'root'

})

export class DataService {

constructor(private http: HttpClient) {}

getData1(): Observable<any> {

return this.http.get('https://api.example.com/data1');

}

getData2(): Observable<any> {

return this.http.get('https://api.example.com/data2');

}

Solution

By using forkjoin

getCombinedData(): Observable<any> {

return forkJoin([this.getData1(), this.getData2()]);

}

combineData() {

this.dataService.getCombinedData().subscribe((responses) => {

const [data1, data2] = responses;

});

By using concatMap: Use concatMap to make sequential HTTP calls and combine their results. This is useful when you want to ensure that the calls are made one after another.

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