i have a problem with ASP.NET Core to share between model and view

Question

In my project I have a login and I want the username to be usable in the .cshtml.

I have it in ASP.NET Core MVC mode and these are my files:

LoginModel.cs

namespace MVC_Catálogo_Imágenes.Models
{
 public class LoginModel
 {
  [Required(ErrorMessage = "Campo obligatorio")]
  public string? User { get; set; }

  [Required(ErrorMessage = "Campo obligatorio")]
  public string? Password { get; set; }
 }
}

Controller.cs:

public ActionResult Login()
{            
   return View();
}

[HttpPost]
public ActionResult Login(LoginModel l)
{
 try
 {
  using (SqlConnection con = new(_contexto.Valor))
  {
   using (SqlCommand cmd = new("sp_login", con))
   {
    cmd.CommandType = System.Data.CommandType.StoredProcedure;
    cmd.Parameters.Add("@Usuario", System.Data.SqlDbType.VarChar).Value = l.User;
    cmd.Parameters.Add("@Pass", System.Data.SqlDbType.VarChar).Value = l.Password;
    cmd.Parameters.Add("@Estado", System.Data.SqlDbType.Bit).Value = 1;
    con.Open();
    object result = cmd.ExecuteScalar();
    int count = result == null ? 0 : Convert.ToInt32(result);
    con.Close();

    if (count > 0)
    {
      IsAuthenticated = true;
      return RedirectToAction("Index", "Home");
    }
    else
    {
      ViewData["error"] = "Usuario y/o contraseña incorrectos";
      return View();
    }
   }
  }
 }
 catch (Exception)
 {
  ViewData["error2"] = "Ha habido un error al iniciar sesión";
  return View();
 }
}

Profile.cshtml

@model LoginModel
<h5>@Model.User</h5>

Well, when calling the model from the view, I get this error:

System.NullReferenceException: 'Object reference not set to an instance of an object.'
Microsoft.AspNetCore.Mvc.Razor.RazorPage.Model.get devolvió null.

Answer 1

(lambdar)

i fixed using cookies:

[HttpPost]
public ActionResult Login(LoginModel loginModel)
{
  Response.Cookies.Append("un", loginModel.User);
  return RedirectToAction("Index", "Home");
}

public ActionResult Profile()
{
  var model = new LoginModel
  {
      User = Request.Cookies["un"]
  };
  return View(model);
}