ErrorHandler & RxJS 6.2.2

Question

I have an application with an globalError handler like this:

import { Injectable, ErrorHandler, Injector } from "@angular/core";
import { Router } from "@angular/router";

@Injectable()
export class GlobalErrorHandler implements ErrorHandler {

  constructor(
    private injector: Injector) { }


  public handleError(error: any) {
    console.error("Something went wrong");
    //.. Handle error here
  }
}

This always worked in every constallation. If an error was thrown the global handler caught it and handled it.

Now after upgrading to RxJs 6.2.2 I understood that catching http errors changed.

Code errors still keep working but errors thrown by the HttpClient are not globally caught. The GlobalErrorHandler is not fired any more.

I am aware that I can handle errors within my service and that works fine like this:

doSomething() {
    return this.http
      .get("http://someURL").pipe(
      map((res: any) => { console.log(res) }),
        catchError(this.handleError<any>(`blabla`))
      );
  }

  /**
 * Handle Http operation that failed.
 * Let the app continue.
 * @param operation - name of the operation that failed
 * @param result - optional value to return as the observable result
 */
  private handleError<T>(operation = 'operation', result?: T) {
    return (error: any): Observable<T> => {
      console.log("Now throwing error");
      // TODO: send the error to remote logging infrastructure
      console.error(error); // log to console instead
      // Let the app keep running by returning an empty result.
      // ToDo: Global Error handler hier aufrufen....
      return of(result as T);
    };
  }

But I actually would like to handle all errors centrally.

What is the correct way with Angular 6 and RxJs 6 to handle errors centrally?

Answer 1

hmm did you try it? In my current Angular 6 application, the global ErrorHandler is called, when nobody else catches the bad HTTP result. Then the event goes through the whole stream, runs into the subscribe callback, doesn´t find a error function and then move directly into the global error handling.

So for me it worked fine. (Angular 6.0.9, RXJS 6.2.1)

I personaly really like to use the specific rxjs error catching most of the time. It allows for specific responses. For some HTTP Errors i want to try a retry, for some it´s okay to work with default values, and for some i have to raise the red flag and let the application die a beautiful death.

The best is, you can catch the error very near to the call, handle it (like do a retry or return a default) and the subscribers want even realize that there was an error handling active.

I´m using the global ErrorHandler and it´s catchAll logic mostly only as last wall of defence.

warm regards