Cannot apply indexing with [] to an expression of type IConfiguration

Question

I have been trying to fix this problem, but nothing comes to mind anymore... Web application to use Tokens, but something keeps me back.

var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_config["Tokens:Key"]));

Here is the whole code:

 namespace DutchTreat.Controllers
{
    public class AccountController : Controller
    {
        private readonly ILogger<AccountController> _logger;
        private readonly SignInManager<StoreUser> _signInManager;
        private readonly UserManager<StoreUser> _userManager;
        private readonly IConfiguration _config;

        public AccountController(ILogger<AccountController> logger, SignInManager<StoreUser> signInManager, UserManager<StoreUser> userManager, IConfiguration config)
        {
            _logger = logger;
            _signInManager = signInManager;
            _userManager = userManager;
            _config = config;
        }
        public IActionResult Login()
        {
            if (this.User.Identity.IsAuthenticated)
            {
                return RedirectToAction("Index", "App");
            }
            return View();
        }
        [HttpPost]
        public async Task<IActionResult> Login(LoginViewModel model)
        {
            if (ModelState.IsValid)
            {
                var result = await _signInManager.PasswordSignInAsync(model.UserName, model.Password, model.RememberMe, false);
                if (result.Succeeded)
                {
                    if (Request.Query.Keys.Contains("ReturnUrl"))
                    {
                        return Redirect(Request.Query["ReturnUrl"].First());
                    }
                    else
                    {
                        return RedirectToAction("Shop", "App");
                    }
                }
            }

            ModelState.AddModelError("", "Failed to login");

            return View();
        }

        [HttpGet]
        public async Task<IActionResult> Logout()
        {
            await _signInManager.SignOutAsync();
            return RedirectToAction("Index", "App");
        }

        [HttpPost]
        public async Task<IActionResult> CreateToken([FromBody] LoginViewModel model)
        {
            if (ModelState.IsValid)
            {
                var user = await _userManager.FindByNameAsync(model.UserName);
                if (user != null)
                {
                    var result = await _signInManager.CheckPasswordSignInAsync(user, model.Password, false);
                    if (result.Succeeded)
                    {
                        //Create the token
                        var claims = new[]
                        {
                            new Claim(JwtRegisteredClaimNames.Sub, user.Email),
                            new Claim(JwtRegisteredClaimNames.Jti, new Guid().ToString()),
                        };

                        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_config["Tokens:Key"]));
                    }
                }

            }

            return BadRequest();
        }
    }
}

Answer 1

The _config.Item["Tokens:Key"] is pretty much legal task, the error seems the Iconfiguration referenced to AutoMapper.Configuration instead of Microsoft.Extensions.Configuration

Answer 2

I'm posting this because you can end up here with the same exact error message if you are accidentally using the wrong namespace for IConfiguration in dotnet core.

Use: using Microsoft.Extensions.Configuration;

Instead of: using Castle.Core.Configuration;