Angular 2 error never get to custom error handler

Question

I've got the simpliest implementation of Angular's (v2.4.3) custom error handler but still can't log errors. What can be wrong?

app.module.ts

providers: [
    { provide: ErrorHandler, useClass: MyErrorHandler }
]

my-error-handler.ts

import { ErrorHandler, Injectable} from '@angular/core';

@Injectable()
export class MyErrorHandler extends ErrorHandler {

  constructor(private errorHandlerService: ErrorHandlerService) {
    super();
  }

  public handleError(error: any): void {
    console.log('error'); // nothing
  }
}

sample-service.ts (trying to throw error)

  addSomething(data) {
    let bodyString = JSON.stringify(data);
    let headers = new Headers({ 'Content-Type': 'application/json' });
    let options = new RequestOptions({ headers: headers });

    return this.http.post(this.url + 'expense', bodyString, options)
      .map((res: Response) => res.json())
      .catch(this.handleError);
  }

  private handleError(error: any) {
    console.log(error.json()); // error: { message: 'Some error' }

    return Observable.throw(error.json());
  }

Error throwed in service never get to MyErrorHandler. What could be wrong?

I don't know if that's important but in console I also got something like this:

POST http://path/to/api 422 // logged by zone.js

coderek · Accepted Answer · 2017-04-03 20:33:45Z

7

change

export class MyErrorHandler extends ErrorHandler {

to

export class MyErrorHandler implements ErrorHandler {

refer to here https://angular.io/docs/ts/latest/api/core/index/ErrorHandler-class.html

And you should also remove the .catch method that short-circuit the error handling

return this.http.post(this.url + 'expense', bodyString, options)
  .map((res: Response) => res.json())
  .catch(this.handleError);      // remove this method call

edited Apr 3, 2017 at 20:33

answered Apr 3, 2017 at 19:56

coderek

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5 Comments

coderek Over a year ago

I think that's because you have specified another handler using .catch method. Remove it, you should be able to see your custom error handler getting called

Mateusz Witkowski Over a year ago

Yes, that's it. Thank you! Can you post it as an answer so I can mark it as a solution?

GFoley83 Over a year ago

Using extends instead if implements frees you up to be able to inject custom services into you MyErrorHandler class, instead of using private injector: Injector.

Crhistian Over a year ago

Shouldn't you also be able to use extends? My understanding is extends allows you to preserve the default functionality and then add to it (which is what I'd like to know how to do). How can I get this to work with extends?

Apoorv Over a year ago

in my case it is getting called twice, any info ?

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