CRUD configuration MVC with Firebase

public string TimestampUtc { get; set; }

@{
    ViewBag.Title = "About";
}
<h2>@ViewBag.Title</h2>

<h3>Login History</h3>
<p>Current user: @ViewBag.CurrentUser</p>
<ul>
    @foreach(var timestamp in ViewBag.Logins)
    {
        <li>Login at @timestamp</li>
    }
</ul>

public async Task<ActionResult> About()
{
  //Simulate test user data and login timestamp
  var userId = "12345";
  var currentLoginTime = DateTime.UtcNow.ToString("MM/dd/yyyy HH:mm:ss");

  //Save non identifying data to Firebase
  var currentUserLogin = new LoginData() { TimestampUtc = currentLoginTime };
  var firebaseClient = new FirebaseClient("yourFirebaseProjectUrl");
  var result = await firebaseClient
    .Child("Users/" + userId + "/Logins")
    .PostAsync(currentUserLogin);

  //Retrieve data from Firebase
  var dbLogins = await firebaseClient
    .Child("Users")
    .Child(userId)
    .Child("Logins")
    .OnceAsync<LoginData>();

  var timestampList = new List<DateTime>();

  //Convert JSON data to original datatype
  foreach (var login in dbLogins)
  {
      timestampList.Add(Convert.ToDateTime(login.Object.TimestampUtc).ToLocalTime());
  }

  //Pass data to the view
  ViewBag.CurrentUser = userId;
  ViewBag.Logins = timestampList.OrderByDescending(x => x);
  return View();
}