Why Dependency Injection doesn't know about my repo? - entity-framework

Question

I have a weird situation. I need to use Entity Framework 6.2 for my .net core app.
An ordinary Controller
public class SampleApiController : BaseController
{
// use _repo and other stuff
}
Base Controller
public class BaseController : Controller
{
protected IRepo_repository;
public BaseController(IRepo repository)
{
_repository = repository;
}
public BaseController() : this(null)
{
}
}
App DBContext
public class SampleContext : DbContext
{
public SampleContext(string connectionString)
:base(connectionString)
{
try
{
this.Database.Log = (s) => System.Diagnostics.Debug.Write(s);
}
catch (Exception e)
{
//CurrentLogger.Log.Error(e);
}
}
public DbSet<Test1> Test1s { get; set; }
public DbSet<Test2> Test2s { get; set; }
}
Repository interface
public interface IRepo
{
// methods definition
}
Repository class
public interface Repo : IRepo
{
// methods implementation
}
Startup.cs -> ConfigureServices method
services.AddScoped<SampleContext>((s) => new SampleContext(configuration["ConnectionStrings:SampleApp"]));
services.AddScoped<IRepo, Repo>();
In this picture you could see that repository param is empty... not initialized with Repo instance... (!!! In this picture IRepo is IRepositoryBase)
Solution !
As CodeNotFound and Riscie said in comments, the problem was that BaseController was initialized with null... Thanks guys!

Answer 1

Try this:
Repository interface
public interface IRepo
{
// methods definition
}
Repository class
I have changed this from interface to class and made it implement the IRepo Interface
public class Repo : IRepo
{
// methods implementation
}
Edit: Also remove the second constructor
public class BaseController : Controller
{
protected IRepo_repository;
public BaseController(IRepo repository)
{
_repository = repository;
}
//second constructor most likely introduces the problem
}

Answer 2

You normally pass IRepo from SampleApiController to BaseController.
Base on my understanding, you do not need no argument constructor in BaseController. If so, you might want to remove it to prevent _repository being null.
public class SampleApiController : BaseController
{
public SampleApiController(IRepo repository)
: base(repository)
{
}
}
public class BaseController : Controller
{
protected IRepo _repository;
public BaseController(IRepo repository)
{
_repository = repository;
}
/*public BaseController() : this(null)
{
}*/
}
public interface IRepo
{
// methods definition
}