Dependency injection in Angular 2 when a constructor has arguments

Question

I have a typescript class representing a model and I would like instances to communicate with an API via angular's Http service.

But the constructor of the model needs arguments when creating instances. For example something super simple:

class SomeModel{
    constructor(public id:number, public name:string, ){
    }

I would like to inject the Http service so it is available to my instances, but it seems like the canonical way to do this commandeers the constructor with:

constructor(http:Http)

I've been digging through the Injector docs, but it's a little sparse and I haven't found anything that works. Is there a way to get a reference to a service like Http from the DI system without using the constructor pattern?

Answer 1

I managed to solve the same problem using angular 4. First you create new injector that uses component injector. It knows about your SomeModel class and passes modelParams as instance of SomeModelParameters class. Then you use this newly created injector to create class instance.

@Injectable()
class SomeModel {
    constructor(http: Http, someModelParamters: SomeModelParameters) { }
}

export class MyComponent {
    constructor(injector: Injector) {
        const modelParams = new SomeModelParameters();
        const injectorWithModelParams = ReflectiveInjector.resolveAndCreate(
            [
                SomeModel,
                { provide: SomeModelParameters, useValue: modelParams }
            ],
            injector);
        this.someModel = injectorWithModelParams.resolveAndInstantiate([SomeModel]);
    }
}