Net Core API Dependency injection without having repository library to be referenced in API project

Question

I am trying to do WEB API project in .NET Core 3.1 with dependancy injection and in Startup class, of my web api project I added this:

public void ConfigureServices(IServiceCollection services)
{
   services.AddControllers();
   services.AddScoped<IMyService, MyService.MyService>(); // <- added MyService as implementation
}

So after that I was able to use service in my controller class

public class BPMController : ControllerBase
{
  private readonly IMyService _myService;

  public MyController(IMyService myService)
  {
    _myService = myService;
  }
}

That's fine. However IMyService is defined in another class library which I called MyDomain and MyService is defined in class library which I called MyService . Now in order to be able to configure MyService as implementation if IMyService in my API project I had to add project reference to both MyDomain and MyService class library. This adds dependency in my API project to MyService project which should be avoided by IoC pattern. I did look at various posts here in stackoverflow, but nowhere I found clear answer. So how to set MyService as implementation of IMyService in my API project without referencing MyService project? It does not matter which IoC container you use in answer (ninject, unity,...)

Answer 1

Ok, after more research, I come to solution which is fine. Back to whiteboard:

In this situation although, I'm using DI, I can instantiate my service with

Service myService = new Service();

which I ultimately wanted to disable (so that no programmer can make that mistake). This could be done by adding another assembly which would contain references to service projects. This assembly (and only this, not services), will be referenced from API project, and role of this assembly is to do dependency injection instead that API project is doing it. Something like this:

What is benefit of this approach? Well, now programmers can't do:

Service myService = new Service(); //we missing Service class

and are forced to instantiate services properly (using DI). That was what I wanted :)