AuthController-1.cs

public class AuthController : Controller
{
    private ApplicationDbContext _db;
    private SignInManager<IdentityUser> _signInManager;
    private UserManager<IdentityUser> _userManager;

    public AuthController(ApplicationDbContext db, SignInManager<IdentityUser> signin, UserManager<IdentityUser> usermanager)
    {
        _db = db;
        _signInManager = signin;
        _userManager = usermanager;
    }
}