ASP.NET MultiLayer App Migration To ASP.NET Core

Question

I migrate my ASP.NET multi layer project to ASP.NET Core. I was using Ninject for DI in my old project and i could call it as follow in my BLL.

public void  IamMethodInBll()
{
    ...
    //i could call ninject like this.
    var prodCalcManager = Const.NinjectKernel.Get<IProdCalcService>();
    prodSurr.CalculatedPrice = prodCalcManager.GetMyMethod()
    ..
}

In now i use ASP Net Core's DI system of course. But how can i call the service locator in business layer for ASP.NET core? I need your samples and suggestions.

In Startup.cs

services.AddScoped<IProdCalcService,ProdCalcManager>();

In BLL

public void  IamMethodInBll()
{
    ...
    //What's the proper way to call another service in BLL
    //How can  i get the service provider in BLL
    var prodCalcManager = _serviceProvider.GetService<IProdCalcService>();
    prodSurr.CalculatedPrice = prodCalcManager.GetMyMethod()
    ..
}

Answer 1

The correct answer is: Dont use ServiceLocator. Register your services using the services.AddScoped<T> like you are and then add that to the constructor of the class you want to use it in.

Like so:

services.AddScoped<IProdCalcService,ProdCalcManager>();

Then your class looks like this:

public class MyClass()
{

    private IProdCalcService calcService;

    public MyClass(IProdCalcService calcService)
    {
        this.calcService = calcService;
    }

    public void IamMethodInBll()
    {

        //...

        prodSurr.CalculatedPrice = calcService.GetMyMethod();

        //...
    }
}

Answer 2

It is better to DONT USE Service Locator but in this case you can inject ServiceProvider to your Controller or better solution is wrap and abstract ServiceProvider in a Container that can be injectable simply. I prefer to use 3rd party DI Containers for use in this situation, specially CastleCore can be good choice.

public interface IContainer 
{
   T Resolve<T>();
}

public class ServiceProviderContainer : IContainer 
{
  private IServiceProvider _serviceProvider; 
  public ServiceProviderContainer(IServiceProvider serviceProvider)
  {
    this._serivceProvider = serviceProvider;
  }

  public T Resolve<T>()
  {
     return _seriveProvider.GetService<T>();
  }
}


public class MyController : Controller 
{ 
  private IContainer contianer;
  public MyController(IContainer container)
  {
    this._container = container;
  }

  public IActionResult Get()
  {
    var service = _container.Resolve<IUserRepository>();
  }
}