How do I return the response from an Observable/ht

Question

I have service which returns an observable which does an http request to my server and gets the data. I want to use this data but I always end up getting undefined. What's the problem?

Service:

@Injectable()
export class EventService {

  constructor(private http: Http) { }

  getEventList(): Observable<any>{
    let headers = new Headers({ 'Content-Type': 'application/json' });
    let options = new RequestOptions({ headers: headers });

    return this.http.get("http://localhost:9999/events/get", options)
                .map((res)=> res.json())
                .catch((err)=> err)
  }
}

Component:

@Component({...})
export class EventComponent {

  myEvents: any;

  constructor( private es: EventService ) { }

  ngOnInit(){
    this.es.getEventList()
        .subscribe((response)=>{
            this.myEvents = response;
        });

    console.log(this.myEvents); //This prints undefined!
  }
}

Answer 1

Observables are lazy so you have to subscribe to get the value. You subscribed it properly in your code but simultaneously logged the output outside the 'subscribe' block. That's why it is 'undefined'.

ngOnInit() {
  this.es.getEventList()
    .subscribe((response) => {
        this.myEvents = response;
    });

  console.log(this.myEvents); //Outside the subscribe block 'Undefined'
}

So if you log it inside the subscribe block then it will log response properly.

ngOnInit(){
  this.es.getEventList()
    .subscribe((response)=>{
        this.myEvents = response;
        console.log(this.myEvents); //Inside the subscribe block 'http response'
    });
}

Answer 2

Also make sure that you map your response to a json output. Otherwise it will return plain text. You do it this like this:

getEventList(): Observable<any> {
let headers = new Headers({ 'Content-Type': 'application/json' });
let options = new RequestOptions({ headers: headers });

return this.http.get("http://localhost:9999/events/get", options)
            .map((res)=>{ return res.json();}) <!-- add call to json here
            .catch((err)=>{return err;})
}