Angular 无提供者的服务注入错误

Question

I have an angular app (v10.1) that is using routing.

In short, I am using modules to take advantage of lazy loading the basic dir structure looks like this

ROOT
    /modules
        /myMod
            myMod.component.ts

the myMod component needs to make use of some services, and so I am trying to include the service (location.service) and declare it in the constructor.

I get an error

core.js:4352 ERROR Error: Uncaught (in promise): 
    NullInjectorError: R3InjectorError(myModModule)[LocationService -> LocationService -> LocationService -> LocationService -> LocationService]: 
    NullInjectorError: No provider for LocationService!

I have tried to add this service to a provider array in @NgModule BUT I have 3 modules to consider ROOT,Resource,myMod

I have tried adding the service to each of these respectively, to no avail - still get the error

Here is a little bit more detailed diagram of the app Please dont tell me I need to add the service to each of the mods, and if Im missusing modules can someone please explain. Thx

ROOT
-app.module
-app-routing.module
-app.component.html (has link routerLink="/resources/myMod" )

-- modules/resources
----resources-routing.module.ts
        const routes: Routes = [{
                path: 'myMod', loadChildren: () => import('../myMod/myMod.module').then((m) => m.myModModule),
            }]

-- modules/myMod
----myMod.module.ts
        import { myModRoutingModule } from './myMod-routing.module';
        import { myModComponent } from './myMod.component';
        @NgModule({
            declarations: [myModComponent],
            imports: [CommonModule, myModRoutingModule]
        })
        export class myModModule {}

----myMod.component.ts
        import { LocationService } from '../../common/services/location.service';
        @Component({
            selector: 'app-myMod',
            templateUrl: './myMod.component.html'
        })
        export class myModComponent implements OnInit {
            constructor( private locationService: LocationService )

https://stackblitz.com/edit/angular-injection-error1

Answer 1

It looks like your @Injectable annotation is missing the providedIn property.

Adding it should resolve the issue:

@Injectable({providedIn: 'root'})
export class LocationService {
  ...
}