How can I make an Angular service injectable only within a specific module?

Question

I am trying to create a service in Angular that should only be injectable within a specific module, not accessible outside that module.

I have a service MyService that I want to restrict so it can only be injected within MyModule and not in other modules of the application.

MyService (my.service.ts):

import { Injectable } from '@angular/core'; 
@Injectable({ 
    providedIn: 'root' // This allows the service to be available globally, which I want to avoid 
})

export class MyService { 
    constructor() {
    } 
}

MyModule (my.module.ts):

import { NgModule } from '@angular/core'; 
import { CommonModule } from '@angular/common';
import { MyService } from './my.service'; 
@NgModule({ 
    declarations: [], 
    imports: [CommonModule], 
    providers: [MyService] // Service should only be injectable here 
}) 
export class MyModule { }

I want MyService to be injectable only within MyModule, and if I try to inject it into components or services in other modules, it should not be available.

I Tried:

1. Providing the service at the module level (providers: [MyService] in MyModule).

2. Avoiding providedIn: 'root' to limit global injection.

How can I ensure that MyService is only injectable within MyModule?

Answer 1

Remove the provideIn when define the service

@Injectable()
export class MyService { ..}

And add in providers of your module

Or inject in the module

@Injectable(
   provideIn:MyModule 
)
export class MyService { ..}

If you're using standalone components and you want two or more component share the same instance of the service check this SO that use Singleton pattern

To check that really the service it's only in the module, you simply try to inject in constructor the service in a component that not belong to the Module. This give you an error in you aplication.

To check it's the same instance of the service, simply declare a variable and change it in any component -in the others the variable of the service will be the same.