How to replace an existing spartacus facade with my own custom implementation?

Question

For example a custom adapter can be easily provided because we have an interface and a default implementation. With implementing the interface and provide the custom implementation in a providers array I can change the implementation on all usages.

Unfortunately for the services in the facade layer are no interfaces, only the implementation.

So the question is how can I provide a custom implementation of a facade (e.g. ActiveCartService) in spartacus and ensure that also usages in the spartacus framework uses my custom implementation?

Answer 1

Supposing you have your custom implementation of ActiveCartService:

import { ActiveCartService } from '@spartacus/core';
import { Injectable } from '@angular/core';

@Injectable()
export class CustomActiveCartService extends ActiveCartService {
  /* .... */
}

Please provide your implementation of ActiveCartService in some module (i.e. in app.module):

@NgModule({
  providers: [
    {
      provide: ActiveCartService,
      useClass: CustomActiveCartService,
    }
  ],
  /* ... */
})
export class AppModule {}