Problems with the ContentByQueryWebPart (CQWP) and its ItemXslLink-property

If you ever tried to set the ItemXslLink (which is a normal property of the ContentByQueryWebPart) you will see that sometimes this simply doesn’t work. You get an exception!

Object reference not set to an instance of an object

Why?

The CmsDataFormWebpart.MakeSiteRelativeUrl (which is called somewhere when setting this property) needs the HttpContext.Current which isn’t available when using a console application or inside an event receiver (déjà vu!).

Solution

Inside the MSDN-Forums a user named AlexUC found a good workaround.

if (null == HttpContext.Current)
{
    HttpRequest request = new HttpRequest ("", web.Url, "");
    HttpContext.Current = new HttpContext (request, new HttpResponse (new StringWriter ()));
    HttpContext.Current.Items["HttpHandlerSPWeb"] = web;
}

Perhaps this even works when one is inside an asynchronous-event inside an event receiver?! Perhaps one can redirect the user inside the ItemAdded-Method?!
I will analyze this soon….