ASP.NET Session Value Manager

ASP.NET Session Value Manager

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.SessionState;

namespace SitefinityWebApp.Utility
{
    public partial class ReferralAuthorizationForm : CustomControl.LoggedInUser
    {
        public DataManager Parameters { get; set; }
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                this.Parameters = new DataManager(this.Session);
            }

            this.Parameters.SetValue(this.Session, DataManager.Keys.DiagnosisID, "Blah blah, your value goes here");

            string test = this.Parameters.GetValue(this.Session, DataManager.Keys.DiagnosisID).ToString();
        }
    }
    
    public class DataManager : SessionManager
    {
        public class Keys
        {
            public static string ReportType = "ReportType";
            public static string ClaimId = "ClaimId";
        }

        public DataManager(HttpSessionState pSession)
        {
            this.PossibleKeys = new List<string>()
            {
                  DataManager.Keys.ReportType
                , DataManager.Keys.ClaimId
            };

            base.Construct(pSession);
        }
    }

    abstract public class SessionManager
    {
        public List<string> PossibleKeys;

        public string GetValue(HttpSessionState pSession, string pKey)
        {
            try
            {
                if (this.PossibleKeys.Contains(pKey))
                    return ((SessionManager)pSession[SessionManager.DefaultKey]).Values[pKey].ToString();                
            }
            catch (Exception e)
            {
                #warning Needs error logging implementation
            }
            //Fallthrough if key isn't right
            return String.Empty;
        }

        public bool SetValue(HttpSessionState pSession, string pKey, string pValue)
        {
            if (this.PossibleKeys.Contains(pKey))
            {
                var tParameters = (SessionManager)pSession[SessionManager.DefaultKey];
                tParameters.Values[pKey] = pValue;
                pSession[SessionManager.DefaultKey] = tParameters;
                return true;
            }
            return false;
        }

        abstract class Keys { }

        private System.Collections.Hashtable Values { get; set; }
        private string SessionKey { get; set; }
        private static string DefaultKey = "parameters";
        
        protected void Construct(HttpSessionState pSession)
        {
            var tCurrentManager = pSession[SessionManager.DefaultKey];
            if (tCurrentManager == null)
            {
                this.Values = new System.Collections.Hashtable();
                foreach (var tKey in this.PossibleKeys)
                {
                    this.Values.Add(tKey, String.Empty);
                }
            }
            else
            {
                var tCurrent = (SessionManager)pSession[SessionManager.DefaultKey];
                this.Values = tCurrent.Values;
            }

            SessionManager.Save(pSession, this);
        }

        // Using a static method here means that we can use the object to save itself
        // to the session during the construction of the object
        private static void Save(HttpSessionState pSession, SessionManager pSelf)
        {
            pSession[SessionManager.DefaultKey] = pSelf;
        }        
    }
}