Creating an SPListItem in a WCF service deployed to SharePoint - wcf

Question

i have the following method in a WCF service, that has been deployed to SharePoint using Shail Malik's guide:
[OperationContract]
public string AddItem(string itemTitle, Guid? idOfListToUse)
{
using (var portal = new SPSite(SPContext.Current.Site.Url, SPContext.Current.Site.SystemAccount.UserToken))
{
using (var web = portal.OpenWeb())
{
Guid listId;
web.AllowUnsafeUpdates = true;
if (idOfListToUse != null && idOfListToUse.Value != new Guid())
{
listId = idOfListToUse.Value;
}
else
{
try
{
listId = new Guid(web.Properties[PropertyBagKeys.TagsList]);
}
catch (Exception ex)
{
throw new MyException("No List Id for the tag list (default list) has been found!", ex);
}
}
var list = web.Lists[listId];
string title = "";
SPSecurity.RunWithElevatedPrivileges(delegate{
var newItem = list.Items.Add();
newItem["Title"] = itemTitle;
newItem.Update();
title = newItem.Title;
});
web.AllowUnsafeUpdates = false;
return title;
}
}
}
When the method gets called from Javascript (using Rick Strahl's excellent ServiceProxy.js) it fails and it does so on newItem.Update() because of ValidateFormDigest().
Here's the kicker though, when I step through the code it works! No exceptions at all!

Answer 1

Ok, found the answer (there's 2 even :-D)
First, the dirty one:
Set FormDigestValidatedProperty in the context:
HttpContext.Current.Items["FormDigestValidated"] = true;
Second, the slightly less dirty version (basically leaving the way open for XSS attacks, but this is an intranet anyway)
The answer

Answer 2

I don't think you can access 'list' as it was created outside the elevated code block.
http://blogs.pointbridge.com/Blogs/herzog_daniel/Pages/Post.aspx?_ID=8
I'm guessing when you are stepping though the entire process is in admin mode so all are elevated.

Answer 3

Colin, it's a really bad idea to try to access HttpContext (likewise SPContext) inside a WCF service. See here: MSDN: WCF Services and ASP.NET
From the article:
HttpContext: Current is always null
when accessed from within a WCF
service.
It's likely this is the cause of your problem.
EDIT: I notice that you're trying to use SPContext to get the url of the site collection. I didn't find a good solution to this either so I just send the url of the target site collection as a parameter to the service call. Not the most optimal solution but I couldn't think of a better way. Also, if you need to check authentication/identities, etc use ServiceSecurityContext.Current.