site wide variables per user

Question

I have an MVC4 site that needs to maintain some information while (and ONLY while) the user is logged in. For example, once the user logs in, I get a \'user token\' back tha

Answer 1

You want to use Session in ASP.net. It was created for the purpose you describe.

ASP.NET session state enables you to store and retrieve values for a user as the user navigates ASP.NET pages in a Web application. HTTP is a stateless protocol. This means that a Web server treats each HTTP request for a page as an independent request. The server retains no knowledge of variable values that were used during previous requests. ASP.NET session state identifies requests from the same browser during a limited time window as a session, and provides a way to persist variable values for the duration of that session. By default, ASP.NET session state is enabled for all ASP.NET applications.

I'm a fan of strongly-typed reusable session variables, so I wrote the following extensions to store whatever variables you want to create without the need to constantly remember magic strings.

public static class SessionExtensions
{
    public static bool TryGetValue<T>(this HttpSessionStateBase session, out T value) 
      where T : class
    {
        var name = typeof(T).FullName;

        value = session[name] as T;

        var result = value != null;

        return result;
    }

    public static void SetValue<T>(this HttpSessionStateBase session, T value)
    {
        var name = typeof(T).FullName;

        session[name] = value;
    }

    public static void RemoveValue<T>(this HttpSessionStateBase session)
    {
        var name = typeof(T).FullName;

        session[name] = null;
    }

    public static bool ValueExists(this HttpSessionStateBase session, Type objectType)
    {
        var name = objectType.FullName;

        var result = session[name] != null;

        return result;
    }
}

So if you have a class:

public MyClass
{
  public int MyInt { get; set; }
}

You can store it by simply:

Session.SetValue(MyClass);

that needs to maintain some information while (and ONLY while) the user is logged in.

These methods could be updated a few ways to fulfill this requirement. Here is one way:

public static bool TryGetAuthenticatedValue<T>(this HttpSessionStateBase session, 
  out T value) 
  where T : class
{
    value = null;

    if (HttpContext.Current.User != null
        && HttpContext.Current.User.Identity != null
        && HttpContext.Current.User.IsAuthenticated)
    {
      var name = typeof(T).FullName;

      value = session[name] as T;
    }

    var result = value != null;

    return result;
}       

I would also recommend that whatever classes you store in session, be serializable. That is to say it has a parameterless constructor and marked as [Serializable].