"The act of initializing an EntryComponent in Angular results in the creation of a brand

In my main component, app.component.ts, I have integrated a new service into the providers[] array and initialized it in the constructor:

@Component({
  selector: 'app-main',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
  providers: [UserService]
})

export class MainComponent implements OnInit {
  constructor( userService: UserService ) {}
ngOnInit(){}
}

Within my primary app module, app.module.ts, there is an entryComponent set up to be displayed within a MatDialog:

// ....
entryComponents: [ProfilePreviewComponent]

Upon launching the dialog, a duplicate instance of my UserService is generated. This results in two separate versions of the same service, causing any changes made within the dialog to not affect the original UserService used by the rest of the application.

What would be the most effective way to prevent this secondary service from being created? Appreciate any insights!

Answer №1

It is recommended to provide services at the module level instead of the component level, as this allows all instances of the service to share the same copy.

Note: This may not hold true if there are components under a lazy loading module that injects this service.

There are two ways to provide a service at the module level in the latest Angular versions:

1. Using providedIn: AppModule or providedIn: 'root'

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

@Injectable({
  providedIn: AppModule,
})
export class AccountService {
}

2. Providing directly inside the module

@NgModule({
  declarations: [
    AppComponent,
    ........
  ],
  .........
  providers: [AccountService],
  bootstrap: [AppComponent]
})
export class AppModule { }

Answer №2

Placing your service within the component will make it exclusive to that specific component. This means that if you have multiple instances of the component, each one will have its own instance of the service.

On the other hand, by providing the service at the module level, it becomes globally accessible. In this scenario, all instances of the component will share a single instance of the service.

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