C# Cannot check Session exists?

Question

I get an error when I do the following:

if(Session[\"value\"] != null)
{
   // code
}

The error i get is this:

Object reference not

Answer 1

The session only really exists during the processing of an action - I wouldn't expect it to be valid in the constructor of a controller. For example, the controller might (for all I know) be re-used between requests.

You will need to do this either in the action (method), or (perhaps more appropriately) in an action filter, or the OnActionExecuting (etc) method(s):

public abstract class ControllerBase : Controller
{
    protected override void OnActionExecuting(
        ActionExecutingContext filterContext)
    {
        // code involving this.Session // edited to simplify
        base.OnActionExecuting(filterContext); // re-added in edit
    }
}