Angular - Not hitting http response callback

Question

Hi I am trying to do something with the result of a http request but my callback is never being executed and I can't wrap my head around why..

I've followed the example from here on this part..

This is my code:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import * as moment from "moment";
import 'rxjs/add/operator/do';
import 'rxjs/add/operator/shareReplay';

@Injectable()
export class AuthdataService {
constructor(private http: HttpClient) {}

login(email: string, password: string) {

  return this.http
    .post("http://localhost:3000/user/login", {
      email,
      password
    })
    .do(res => this.setSession)
    .shareReplay();
  }

  private setSession(authResult) {
  console.log("Why am I not being hit???")
  const expiresAt = moment().add(authResult.expiresIn,'second');

  localStorage.setItem('id_token', authResult.idToken);
  localStorage.setItem("expires_at", JSON.stringify(expiresAt.valueOf()) );
  }  
}

---

Updated solution:

login(email: string, password: string) {

return this.http
  .post("http://localhost:3000/user/login", {
    email,
    password
  })
  .do(res => this.setSession(res))
  .shareReplay();   
  }

Answer 1

You are expecting the Observable sequence you're creating to be "hot", but instead it is "cold". The difference is described elsewhere on the internet in terms better than I can manage.

In other words, the .post doesn't actually do anything until it is subscribed to. Reference.

Invoking shareReplay doesn't subscribe to the Observable, but only ensures that up to one subscription to the underlying Observable will ever be created at once.

So the missing link is probably a call to .subscribe on the Observable you have created.