Null object cannot be converted to a value type exception is thrown inside ProcessRequest Method

Question

I am able to get the CurrentSideId, I can say anywhere through the application. I have a class called MainClass. It has static CurrentSideId property. MainClass.CurrentSiteId returns the SiteId requested.

public class MainClass{
   public static int CurrentSiteId
   {
      get { return HttpContext.Current.Request.RequestContext.RouteData.Values["CurrentSiteId"].To<int>(); }
      set {..}
   }
}

But, when it comes to ProcessRequest method of the HttpHandler, CurrentSiteId throws an exception of type System.InvalidCastException: Null object cannot be converted to a value type.

public class MyRouteHandler : MvcRouteHandler
{
    protected override IHttpHandler GetHttpHandler(RequestContext requestContext)
    {
        return new MyHttpHandler();
    }
}
public class MyHttpHandler : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        var siteId = MainClass.CurrentSiteId;
    }
}

What would be the resolution?

What isn't clear about the error message? `Values` returns `null` because the key doesn't exist, hence it returns `null`, which you try to convert to an `int`. — Yuval Itzchakov, Mar 10 '15 at 08:51

hutchonoid · Answer 1 · 2015-03-10T13:21:33.877

1

You should be able to access it via context providing the route value is passed in:

Convert.ToInt16(context.Request.RequestContext.RouteData.Values["CurrentSiteId"]);

Update

Try the following:

public class MyHttpHandler : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        var siteId = Convert.ToInt16(context.Request.RequestContext.RouteData.Values["CurrentSiteId"]);
    }
}

edited Mar 10 '15 at 13:21

answered Mar 10 '15 at 09:28

hutchonoid

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I have already tried. There is no `To` extension for `Values["CurrentSiteId"]`. – Jude Mar 10 '15 at 09:36
@Jude I think you must either include the namespace for the extension method. If you go to definition of the `To` method you will see that or use the above. I changed it to use `Convert.ToInt16` instead. – hutchonoid Mar 10 '15 at 09:55
This only gives me the Controller Name and the Action Name. There seems no "CurrentSiteId" key. – Jude Mar 10 '15 at 12:26
@Jude The calling application must not be passing it across, what is calling it? – hutchonoid Mar 10 '15 at 12:36
Edited the question. Added RouteHandler. Does this answer your question? – Jude Mar 10 '15 at 13:01
@Jude try the update just to see if you can get it outside of the class – hutchonoid Mar 10 '15 at 13:21

score 0 · Answer 2 · edited May 23 '17 at 11:43

0

you should check that the value is not null before casting it a good sample can be found here: In MVC3, how to get the current action name? (replace action with the method you want to call)

edited May 23 '17 at 11:43

Community

1
1

answered Mar 10 '15 at 08:54

Sim1

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Null object cannot be converted to a value type exception is thrown inside ProcessRequest Method

2 Answers2