Angular2 DI - initializing multiple different instances in the same constructor

Question

I have an Angular2 DI question. Say I have a TestService and I want to use 2 different instances of this service inside the same component. If I simply add a pr

Answer 1

Given that there is finite amount of instances, the straightforward way may be:

@Component({
    providers: [
        { provide: 'TestService1', useClass: TestService },
        { provide: 'TestService2', useClass: TestService }
    ]
})
export class TestComponent implements OnInit {
    constructor(
        @Inject('TestService1') private _testService1: TestService,
        @Inject('TestService2') private _testService2: TestService
    ) {}
    ...
}

Or OpaqueToken counterpart to avoid overriding services with the same string identifier:

export const TestService1 = new OpaqueToken;
export const TestService2 = new OpaqueToken;

...
providers: [
    { provide: TestService1, useClass: TestService },
    { provide: TestService2, useClass: TestService }
]
...
constructor(
    @Inject(TestService1) private _testService1: TestService,
    @Inject(TestService2) private _testService2: TestService
) {}

It doesn't hurt DI in TestService constructor. And keeps the testability of TestComponent on par, both service instances can be mocked independently.