No More Session Variable Misspellings

This can be automated and streamlined with generics. First, create a SessionVariable class:

public class SessionVariable<T>
{
    private string VariableName { get; set; }
    private System.Web.SessionState.HttpSessionState Session { get; set; }
    public T Value
    {
        get
        {
            object sessionValue = this.Session[this.VariableName];
            if (sessionValue == null)
            {
                sessionValue = default(T);
            }
            return (T)sessionValue;
        }
        set
        {
            this.Session[this.VariableName] = value;
        }
    }
    public SessionVariable(string variableName,
        System.Web.SessionState.HttpSessionState session)
    {
        this.VariableName = variableName;
        this.Session = session;
    }
}

Next, create a SessionHelper class:

using System;
using System.Reflection;
public class SessionHelper
{
    public static void InitializeSessionVariables(object instance,
        System.Web.SessionState.HttpSessionState session, string prefix)
    {
        foreach (var property in instance.GetType().GetProperties(
            BindingFlags.Public | BindingFlags.Instance))
        {
            if (property.PropertyType.IsGenericType &&
                property.PropertyType.GetGenericTypeDefinition() ==
                typeof(SessionVariable<>))
            {
                property.SetValue(instance, Activator.CreateInstance(
                    property.PropertyType, prefix + property.Name, session),
                    new object[] { });
            }
        }
    }
}

You can then add properties to your page (or another suitable class) that act as a simple way to access session. Here is an example:

public partial class Default : System.Web.UI.Page
{
    public SessionVariable<string> CompanyName { get; set; }
    public SessionVariable<int> EmployeeCount { get; set; }
    public SessionVariable<System.Text.StringBuilder> CompanyInformation { get; set; }
    protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);
        SessionHelper.InitializeSessionVariables(this, Session, "Default.aspx.");
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        CompanyName.Value = "Code Project";
        EmployeeCount.Value = 5;
        Response.Write(CompanyName.Value);
        Response.Write(EmployeeCount.Value.ToString());
        Response.Write((CompanyInformation.Value ??
            new System.Text.StringBuilder("Company information null")).ToString());
    }
}

That is my code behind for my Default.aspx page. Notice I added 3 generic properties of type SessionVariable. Next, I initialized those properties using my helper method, InitializeSessionVariables (note that I passed in a prefix to ensure the session variables would not conflict with those used on other pages). Finally, I demonstrated their use in the Page_Load method. This makes creating session variables type safe and prevents mistyping session variable names.