Angular2 Http - No Errors, No Connection

Question

I am having a really hard time determining what is wrong with my code. I am trying to create a service class to connect to my separate database application which exposes an open (unsecure) REST API.

If I connect to the address in my browser I can correctly see the results, and a connection is logged on my server. However when I try to connect via my Angular2 service class I get no errors and no connection attempt on my server.

I have been rewriting the below over and over again, reading the docs and cannot figure it out! I am using 2.0.1.

import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Headers, RequestOptions } from '@angular/http';
import { Observable } from 'rxjs/Rx';

@Injectable()
export class AuthenticationService {

  private loggedIn = false;
  private loginUrl = 'http://localhost:3000/api/users';

  constructor(private http: Http) { }

  login(user:any): Observable<any[]> {

    var x = this.http.get(this.loginUrl)
                    .map(this.extractData)
                    .catch(this.handleError);

    console.log(x);
    console.log("Sent?");

    return null;
  }

  private handleError (error: any) {
    let errMsg = (error.message) ? error.message :
      error.status ? `${error.status} - ${error.statusText}` : 'Server error';
    console.error(errMsg); // log to console instead
    return Observable.throw(errMsg);
  }

  private extractData(res: Response) {
    let body = res.json();
    return body.data || { };
  }
}

In my console I see the results of console(x) and console('sent?') so I know the code is being executed.

Have you injected HttpModule in app.module or main.module file??? — micronyks
– micronyks, Commented Oct 17, 2016 at 17:07
You can use return x; instead of return null; and in component you can subscribe to login method... — micronyks
– micronyks, Commented Oct 17, 2016 at 17:10

Günter Zöchbauer · Accepted Answer · 2016-10-17 17:17:43Z

1

Without subscribe() or toPromise() an Observable isn't doing anything because they are lazy

var x = this.http.get(this.loginUrl)
                .map(this.extractData)
                .catch(this.handleError);

This way it makes the request

var x = this.http.get(this.loginUrl)
                .subscribe(this.extractData, this.handleError);

You need to be cautious about using thin. in extractData and handleError. It's usually better to always use arrow functions

var x = this.http.get(this.loginUrl)
                .subscribe(data => this.extractData(data), 
                           err => this.handleError(err));

edited Oct 17, 2016 at 17:17

answered Oct 17, 2016 at 17:07

Günter Zöchbauer

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1 Comment

Steven Over a year ago

Ah awesome thanks! Will accept as soon as I am allowed.

Alexander Ciesielski · Accepted Answer · 2016-10-17 17:09:09Z

1

Your forgot to subscribe to the http.get call.

You need to type:

 http.get(...).subscribe(data => console.log(data));

to make the actual call.

Observables are cold, that means without subscribing nothing happens.

answered Oct 17, 2016 at 17:09

Alexander Ciesielski

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