Question

At times when we access Session["key"].ToString() it gives exception when session is expired & in coding we try to access session variable. So I’m trying to create extension method on object class so that I could write it as Session["key"].getString() in coding so that every time I don’t have to do Convert.ToString(session["key"])

Any other solutions are also appreciable.

Answer 1

Just use the null-coalescing operator:

string value = (session["key"] ?? String.Empty).ToString();

Update
If you must have a method to do this (extension or otherwise), I would do something like:

public static string GetValue(this HttpSessionState session, string key)
{
   // TODO: Insert appropriate error checking here.

   return (session[key] ?? String.Empty).ToString();
}

I might even go so far as to make it generic for other possible types with a GetValue call that takes a selector and then use lambdas:

public static T GetValue<T>(this HttpSessionState session, string key, Func<object, T> valueSelector)
{
    return valueSelector(session[key]);
}

public static string GetStringValue(this HttpSessionState session, string key)
{
    return session.GetValue(key, x => (x ?? String.Empty).ToString());
}

You would then use as follows:

string value = session.GetStringValue("key");