Is this method of creating a HTTP Service in Angular correct?

Question

This is the HTTP Service, makes a get request that fetches longArray.js;

import { Injectable } from '@angular/core'; import { Http } from '@angular/http'; import 'rxjs/Rx'; @Injectable() export class HttpService { constructor( private http: Http ) {} getHttpReq(url: string): Promise<any> { return new Promise((resolve, reject) => { this.http.get('http://192.168.0.189/longArray.js') .map(response => response.json()) .subscribe( function(response) { console.log("Success Response "); resolve(response); }, function(error) { console.log("Error happened " + error); reject(error); }, function() { console.log("Subscription is completed "); } ); }); } }

This is a method that returns a bool promise depending on if longArray.js was fetched by getHttpReq (in class HttpService) or not;

getLongArrayTryOrFail(): Promise<boolean> { return new Promise((resolve,reject) => { this.httpService.getHttpReq('') .then(response => resolve(true)) .catch(error => reject(false)) }); }

Is this method of creating HTTP Service correct?
Basically getHttpReq (in class HttpService) Subscribes to an Observable & either resolves or rejects the promise depending on subscription's successful response or error. Am I correct?

If you really want to return a promise, then just use toPromise() on the observable returned by http.get. — user663031
– user663031, Commented Jun 20, 2017 at 4:45

Pankaj Parkar · Accepted Answer · 2017-06-20 04:52:02Z

Is this method of creating HTTP Service correct?

No, generally you shouldn't be consider using Promise with Observable.

Basically getHttpReq (in class HttpService) Subscribes to an Observable & either resolves or rejects the promise depending on subscription's successful response or error. Am I correct?

There isn't any problem with your Promise implementation, but I don't understand why you're running away from using Observable. It has everything what you're looking for + they are lazy. Below is Observable implementation of the same in few lines of code.

Code

export class HttpService { constructor( private http: Http ) {} getHttpReq(url: string): Observable<any> { return this.http.get('http://192.168.0.189/longArray.js') .map(response => response.json()); }); } } //consumption getLongArrayTryOrFail(): Observable<boolean> { return this.httpService.getHttpReq('') .map(response => true) .catch(error => Observable.throw(false)); }); }

@torazaburo map should do the trick. thanks for heads up. :) If I would have switchMap then I need to explicitly return Observable from there.. correct??

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