public class UserController : Controller
{
    // GET
    [HttpGet]
    public IActionResult Login()
    {
        return View();
    }
    
    // get login datas
    [HttpPost]
    public async Task<IActionResult> Login(string username, string password)
    {
        LoginMatcher lm = new LoginMatcher(username, password);
        User? user = lm.Loginner();
        if (user != null)
        {
            Console.Out.WriteLine("giriş başarılı");
            return Json(new { status="error",message="acces accept"});
        }
        else
        {
            ViewData["Login"] = "wrong_password";
            return View();
        }
        
    }
}

public class UserController : Controller
{
    // GET
    [HttpGet]
    public IActionResult Login()
    {
        return View();
    }
    
    // get login datas
    [HttpPost]
    public async Task<IActionResult> Login(string username, string password)
    {
        LoginMatcher lm = new LoginMatcher(username, password);
        User? user = lm.Loginner();
        if (user != null)
        {
            Console.Out.WriteLine("giriş başarılı");
            return Json(new { status="error",message="acces accept"});
        }
        else
        {
            ViewData["Login"] = "wrong_password";
            return View();
        }
        
    }
}

                    @if (ViewData["Login"] == "wrong_password")
                    {
    
                        <div class="login-wrong-password">
                            <span>Kullanıcı adı veya parola hatalı!</span>
                        </div>
                        
                    }
                    

                    @if (ViewData["Login"] == "wrong_password")
                    {
    
                        <div class="login-wrong-password">
                            <span>Kullanıcı adı veya parola hatalı!</span>
                        </div>
                        
                    }