Unable to resolve service for type while attempting to activate

Question

I have one file Repository.cs that contains an interface and its implementation like so:

public interface IRepository

{
    IEnumerable

        

Answer 1

A method like this needs to be added to your Startup:

    // This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
    //...

    // Add application services.
    services.AddTransient();

    //..
}

Services should be registered before used.

UPDATE: If you do not want to use DI on your application, just create and instance of MemoryRepository on the constructor of HomeController, like this:

public class HomeController : Controller
    {
        private IRepository repository;

        public HomeController()
        {
            repository = new MemoryRepository();
        }

        public IActionResult Index()
        {
            return View(repository.Cities);
        }

    }