public async Task <IActionResult> OnPostAsync()
        {
            if (!ModelState.IsValid)
            {
                return(Page());
            }

            var loginModel = new LoginModel {
                UserName = UserName, Password = Password
            };

            try
            {
                if (!await _apiManager.DoLogin(loginModel))
                {
                    Error = "You don't exist, go away!";
                    return(Page());
                }
            }
            catch (Exception ex)
            {
                Error = string.Format("An error occurred: {0}", ex.Message);
            }

            return(RedirectToPage("/Devices"));
        }