Error using current SPWeb from HttpModule

Question

Is it allowed to access SPWeb and specifically SPWeb.ID from PreRequestHandlerExecute ?

Writing an HttpModule [SharePoint2010] and trying to access current web ID using this line of code :

private void context_PreRequestHandlerExecute(object sender, EventArgs e)
{
Guid  curID = Microsoft.SharePoint.WebControls.SPControl.GetContextWeb(System.Web.HttpContext.Current).ID;
}

All seems fine but when using the designer, an error is generated :

"soap:ServerServer was unable to process request. ---> Cannot complete this action.     Please try again. ---> Cannot complete this action. Please try again."

EDIT : Note that SPContext works fine in PreRequestHandler, it exists and all fields returh the correct values. During QA, we found out that accessing Spweb.ID causes the Desginer to throw an error .. this is disturbing since there might be implications of using SPContext which are not documented at all.

Answer 1

You can try to use somwthing like this

    public void Init(HttpApplication application) {
        application.BeginRequest += (new EventHandler(this.Application_BeginRequest));
        application.EndRequest += (new EventHandler(this.Application_EndRequest));
    }

    // Your BeginRequest event handler.
    private void Application_BeginRequest(Object source, EventArgs e) {
        HttpApplication application = (HttpApplication)source;
        HttpContext context = application.Context;
        SPContext spctx = SPContext.GetContext(context);
    }

Answer 2

Remember that your HTTP Module effectively runs outside SharePoint. It won't have things like an SPContext yet.

I would try using the requested URL to get the current web:

string url = "http://sp/somesite/lists/somelist/etc";
using(SPSite site = new SPSite (url) {
  using(SPWeb currentWeb = site.OpenWeb(){
    //CurrentWeb should contain the site that the request refer to.
  }
}

Answer 3

I've had the same issue. I also used the PreRequestHandlerExecute event of the HTTPModule, because I needed SPContext (which is not available yet in BeginRequest).

The reason why SPD wasn't working for my situation was that SPD did a request to '_vti_bin/WebPartPages.asmx' which results in a 'Internal Server Error' when my custom HTTPModule was handling the request. Unknown why, because I was only handling particular request and ignoring other onces.

But I managed to fix it with the code below. When a request comes in with a '.asmx' extension or 'owssvr.dll' (which was also causing problems with my custom HTTPModule, when changing List Settings), the request is just ignored with simply calling 'return';

 void context_PreRequestHandlerExecute(object sender, EventArgs e)
 {    
     var context = HttpContext.Current;
     string absolutePath = context.Request.Url.AbsolutePath.ToLower();
     if (absolutePath.Contains("owssvr.dll") ||
         absolutePath.Contains(".asmx"))
     {
        return;
     }

     //Your custom code
 }