How to throw an observable error manually?

Question

I am working on an Angular app in which I am making a rest call through HTTP as below:

login(email, password) {
    let headers = new Headers();
    headers.a         


        

Answer 1

Use the catch operator

this.calcSub = this.http.post(this.constants.userUrl + "UpdateCalculation", body, { headers: headers })
   .map((response: Response) => {
      var result = response.json();
         return result;
   })
   .catch(this.handleError)
   .subscribe(
      dro => this.dro = dro,
      () => this.completeAddCalculation()
   );

And handle the error like this:

private handleError(error: Response) {
    console.error(error); // log to console instead
    return Observable.throw(error.json().error || 'Server Error');
}