How should I keep UserId (in a hidden input or as session value)

Hi all,

In a SPA I need to use UserID to save related data.

I use  <input id="UserId" hidden value="@Model.Id" /> this technique to get it.

But what about havving a session and keep the UserId there?

Is it safer ?

But if connection is gone and come back while typing session data also may have gone and it may cause unwanted errors

If I am thinking right because I don't have experience in that area