How I use "Interval" or similar on an Http Observable? - angularjs

Question

I'm fairly new to AngularJS (2.0.0-beta.16). I've managed to setup a service that pulls data from an API, via a GET request. Now, how do I set it up to run the GET request every n seconds? I've seen other posts saying you could just using this._http.get(...).interval(5000).map(...);, however when I've tried that, I get a Typescript compilation error:
Property 'interval' does not exist on type 'Observable'.
Am I making a silly mistake or is there a better pattern for doing this?
import { Injectable } from 'angular2/core';
import { Http, Response } from "angular2/http";
import { Observable } from "rxjs/Observable";
import * as _ from "js/lodash.js";
import { Foo } from "./foo";
#Injectable()
export class FooService {
fooList: Observable<Foo[]>;
constructor(private _http: Http) {
this.fooList = this._http.get('http://localhost:9090/api/').map(
response => {
var json = response.json();
if(response.ok === true) {
let newFooList: Foo[] = [];
_.forEach(json, f => {
newFooList.push(new Foo(f));
});
return newFooList;
}
throw Error("Bad status: " + response);
});
}
}

Answer 1

This is probably not the only (or the best) way, but it worked for me. The only issue is that the first GET request is delayed by the amount of time specified by create().
import { Injectable } from "angular2/core";
import { Http, Response } from "angular2/http";
import { Observable } from "rxjs/Observable";
import { IntervalObservable } from "rxjs/observable/IntervalObservable";
import * as _ from "js/lodash.js";
import { API_URI } from "./constants";
import { Foo } from "./foo";
#Injectable()
export class FooService {
public fooList: Observable<Foo[]>;
constructor(private _http: Http) {
this.fooList = IntervalObservable.create(2000).flatMap(
() => {
return this._http.get(API_URI);
}).map(
response => {
var json = response.json();
if(response.ok === true) {
let newFooList: Foo[] = [];
_.forEach(json, f => {
newFooList.push(new Foo(f));
});
return newFooList;
}
throw Error("Bad status: " + response);
});
}
}