Angular 2 injector can't find Service when loading CustomExceptionHandler

Question

When trying to inject a service into my CustomExceptionHandler, the Angular injector cannot find the service.

The error: Uncaught Can't resolve all parameters for CustomExceptionHandler: (?).

The setup:

CustomExceptionHandler

import { ExceptionHandler } from '@angular/core';

import { ServiceA } from '../services/a.service';

export class CustomExceptionHandler extends ExceptionHandler {

  constructor(private serviceA: ServiceA) {
    super(null, null);
  }

  call(error, stackTrace = null, reason = null) {
      //do something with the service
  }
}

app.module

@NgModule({
  declarations: [
    ...
  ],
  imports: [
    ...
  ],
  providers: [
    ServiceA,
    { provide: ExceptionHandler, useClass: CustomExceptionHandler },
  ],
  bootstrap: [AppComponent],
})
export class AppModule { }

`import { Service } from '../services/a.service';` should probably be `import { ServiceA } from '../services/a.service';` (missing `A` in the service name) — Günter Zöchbauer, Sep 19 '16 at 15:25

score 1 · Answer 1 · edited Sep 19 '16 at 15:24

1

You need to add CustomExceptionHandler and its dependencies to providers as well:

@NgModule({
  declarations: [
    ...
  ],
  imports: [
    ...
  ],
  providers: [
    ServiceA,
    CustomExceptionHandler,
    { provide: ExceptionHandler, useClass: CustomExceptionHandler },
  ],
  bootstrap: [AppComponent],
})
export class AppModule { }

edited Sep 19 '16 at 15:24

Daniel Patrick

3,980
6
29
49

answered Sep 19 '16 at 15:21

Günter Zöchbauer

623,577
216
2,003
1,567

I've revised the error: `Uncaught Can't resolve all parameters for CustomExceptionHandler: (?).` – Daniel Patrick Sep 19 '16 at 15:24
this isn't it, the issue persists. thank you for your time though – Daniel Patrick Sep 19 '16 at 15:26
thank you both Gunter and ade for your answers. it was the combination of both of these that fixed it. You need to add @Injectable() and you need to list it as a normal provider in the app.module.ts in addition to listing it as a useClass to override the ExceptionHandler. This leaves me with somewhat of a predicament for who to accept as the answer. Whomever types up the combination of these will get it. Thanks again! – Daniel Patrick Sep 19 '16 at 15:32
1

Everyone has to start somewhere. I didn't start with 100k neither ;-) – Günter Zöchbauer Sep 19 '16 at 15:39

score 1 · Accepted Answer · edited May 23 '17 at 12:17

1

update ExceptionHandler was renamed to ErrorHandler https://stackoverflow.com/a/35239028/217408

orgiginal

Add @Injectable() to your CustomExceptionHandler class.

Add CustomExceptionHandler as another one of your providers in the app.module.ts:

@NgModule({
  declarations: [
    ...
  ],
  imports: [
    ...
  ],
  providers: [
    ServiceA,
    CustomExceptionHandler,
    { provide: ExceptionHandler, useClass: CustomExceptionHandler },
  ],
  bootstrap: [AppComponent],
})
export class AppModule { }

edited May 23 '17 at 12:17

Community

1
1

answered Sep 19 '16 at 15:27

ade jones

639
11
15

thank you both Gunter and ade for your answers. it was the combination of both of these that fixed it. You need to add @Injectable() and you need to list it as a normal provider in the app.module.ts in addition to listing it as a useClass to override the ExceptionHandler. This leaves me with somewhat of a predicament for who to accept as the answer. Whomever types up the combination of these will get it. Thanks again! – Daniel Patrick Sep 19 '16 at 15:32

Angular 2 injector can't find Service when loading CustomExceptionHandler

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