Angular2 - Handling API Response - node.js

Question

Good afternoon! I'm new in Angular 2, so I'm sorry in advance if my question is generic. I cannot figure out how to handle an API response.
My NodeJS Server API function is (Checked and works fine):
router.get('/appointment/:iatreio/:time', function(req, res, next) {
var paramIatreio = req.params.iatreio;
var paramTime = req.params.time;
db.appointments.findOne({iatreio: paramIatreio, time: req.params.time}, function(err, resultFound) {
if (err) { res.send(err); }
if (resultFound) {
res.json(true); // 1st Question: For best practice, res.json(true) or res.send(true)?
} else {
res.json(false);
}
});
});
My Angular2 Service:
import { Injectable } from '#angular/core';
import { Headers , Http } from '#angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
#Injectable()
export class AppointmentService {
constructor(private http: Http) { }
isBooked(iatreio: string, time: string): Observable<boolean> {
return this.http
.get('http://localhost:3000/appointment/'+iatreio+'/'+time)
.map(); //2nd Question: What inside map()?
}
} // end of Service
Component Function
isBooked(selectedIatreio: string, selectedTime: string): boolean {
this.appointmentService
.isBooked(selectedIatreio, selectedTime)
.subscribe(() => {}); //3rd Question: What inside subscribe()?
}
My final goal is the "isBooked(...)" function of my Component to be called and to return true or false. I have seen the code in the examples in the Angular2 site, but I'm a little confused on my case.
Can Service function return directly a true or false value or it has to be an Observable?? Map() function is necessary??
Generally, my thinking is right?? Or my goal can be accomplished more easily??
Thank you a lot for your time!!

Answer 1

map is used to convert the response into the model which you look for
isBooked(iatreio: string, time: string): Observable<boolean> {
return this.http
.get('http://localhost:3000/appointment/'+iatreio+'/'+time)
.map((response)=><boolean>response.json());
}
subscribe will return the data emitted by the service
isBooked(selectedIatreio: string, selectedTime: string): boolean {
this.appointmentService
.isBooked(selectedIatreio, selectedTime)
.subscribe((data) => {
//your operation
console.log(data);
});
}