c# - Session variable is reset after making a request to Web API controller -

i'm using session in web api implementing follow answer enable session in web api 2. got problem session variables.

in business object class, have property used store changed record.

public class basebo {   protected httpsessionstate _session;    public basebo()   {       _session = httpcontext.current.session;   }    private ilist<fundinvestor> _investors;   public  ilist<fundinvestor> investors   {         {         _investors = (ilist<fundinvestor>)_session["_investors"];         if (_investors == null)         {             _investors = new list<fundinvestor>();             _session["_investors"] = _investors;         }         return _investors;     }     set     {         _investors = value;         _session["_investors"] = value;     }   }  } 

at client, when saving form, make 2 requests server. first, call method addinvestorqueue of basebo instance list of changed records. changed records added list investors of basebo. second request, call method edit in element of list investor , update these records database.

my problem list investors doesn't have element when call second request. note there records added investors in first request. don't know why list reset.

this issue doesn't occurs when use asp.net web form.

is there met similar issue? stuck issue. advice helpful me. thank much.