Angular2: Why does 'else' not get executed in subscribe function?

Question

I'm trying to verify that the response email field matches the email to the user which is logged-in. When I navigate to an URL (detail/:id) which was set up by another user and doesn't belong to the currently logged-in user, Angular should display an error message.

So far so good. But in my case, the else function, to display the correct response does not get executed. Also console.log(appointmentDetails); doesn't give me any output.

I already tested the template view as I inverted the if-statement. So this would work.

UPDATE: The appointmentDetails = [0]; makes me confused.

Valid JSON response:

{
  id: 241772331,
  firstName: "Justin",
  lastName: "Miller",
  email: "justin@miller.com", ...
} 

Error JSON response:

{
  success: false,
  message: 'You are not authorized to edit this apoointment.'
}

Template view:

<div class="row show-hide-message" *ngIf="message">
  <div [ngClass]="messageClass">
    {{ message }}
  </div>
</div>

<div class="box">
  {{ appointmentDetails.type }}
  {{ appointmentDetails.firstName }}
  {{ appointmentDetails.lastName }}
</div>

AppointmentDetailComponent:

export class AppointmentDetailComponent implements OnInit {
  username = '';
  email = '';
  message;
  messageClass;
  getData: any;
  appointmentDetails = [0];
  id: number;
  private sub: any;

  constructor(
    private authService: AuthService,
    private apiService: ApiService,
    private route: ActivatedRoute
  ) {}

  ngOnInit() {
    this.sub = this.route.params.subscribe(params => {
      this.id = +params['id']; // (+) converts string 'id' to a number
    });
    this.getData = this.getDataFunction;
    this.getData();
  }

  getDataFunction() {
    this.authService.getProfile().subscribe(profile => {
      this.username = profile.user.username; // Set username
      this.email = profile.user.email; // Set e-mail
      if (profile.user.email) {
        console.log(this.id);
        this.apiService
          .getAppointmentDetailsById(this.id, this.email)
          .subscribe(appointmentDetails => {
            if (!appointmentDetails.success) {
              this.messageClass = 'alert alert-danger'; // Set error bootstrap class
              this.message = appointmentDetails.message; // Set error message
            } else {
              console.log(appointmentDetails);
              this.appointmentDetails = appointmentDetails;
            }
          });
      }
    });
  }

  ngOnDestroy() {
    this.sub.unsubscribe();
  }
}

Server API route:

const url = process.env.acuityUri + '/appointments/' + id;
fetch(url)
  .then(response => response.json())
  .then(json => {
    if (json.email === user.email) {
      res.json(json);
    } else {
        res.json({
          success: false,
          message: 'You are not authorized to edit this apoointment.'
        });
      }
    });

Answer 1

It seems you are just returning two different objects in the success and failure scenarios and not throwing any error. So you must do the check in the first block of subscribe itself. No need to have the error block. So look for the property as a condition

So, use

this.apiService
  .getAppointmentDetailsById(this.id, this.email)
  .subscribe(appointmentDetails => {
    if (!appointmentDetails.hasOwnProperty('success') {
      this.messageClass = 'alert alert-danger'; // Set error bootstrap class
      this.message = appointmentDetails.message; // Set error message
    } else {
      console.log(appointmentDetails);
      this.appointmentDetails = appointmentDetails;
    }
  });

Answer 2

Try the following way,

this.apiService
  .getAppointmentDetailsById(this.id, this.email)
  .subscribe(appointmentDetails => {
      console.log(appointmentDetails);
      this.appointmentDetails = appointmentDetails;
    }, (error) => {
      this.messageClass = 'alert alert-danger'; // Set error bootstrap class
      this.message = error.message;
  });