Impersonation in SharePoint is not really the hardest to do. However the C# code snippet below was sort of new for me. In order to obtain impersonation for a DataContext, that was something.

Impersonation for the ClientContext … but the LINQ DataContext is constructed in another way… and by default using the current user… regardless the user you’ve set in SPContext.

So… here it is.

strUrl = SPContext.Current.Web.Url;

HttpContext backupContext = HttpContext.Current;
try
{
  SPUserToken userToken = null;
  userToken = SPContext.Current.Web.AllUsers[“SHAREPOINT\\system”].UserToken;

  // if there is a SPContext make it is as null so LINQ won’t execute under current context
  if (SPContext.Current != null)   HttpContext.Current = null;

  SPSecurity.RunWithElevatedPrivileges(delegate() {
    using (SPSite oSite = newSPSite(strUrl, userToken)) {
      using (SPWeb oWeb = oSite.OpenWeb()) {
                               // creating a new HttpContext under elevated permission and
             // setting it as current control context web,
             // because of this the code will be running under elevated permission.

        HttpRequest httpRequest = newHttpRequest(“”, oWeb.Url, “”);
        HttpContext.Current = newHttpContext(httpRequest, new HttpResponse(new System.IO.StringWriter()));
        SPControl.SetContextWeb(HttpContext.Current, oWeb);

        using (SomeDataContext dc = SomeDataContext(oWeb.Url)) 
        {
          var comments = from c in dc.SomeDataContext
                         where c.Var1 == someVariable 
                         select c;
                    }
      }
    }
  });

}

catch (Exception ex) {}
finally {
   // make sure that you are setting the actual SPContext back
   // after your operation and make SharePoint happy J

   if (SPContext.Current != null) HttpContext.Current = backupContext;
}

Already struggling with the poor functionality of the web service interface of the Taxonomy web service of SharePoint 2010, I stumbled upon another challenge.

I was building a MS CRM 2011 Plugin that populates the SharePoint Term Store using the Taxonomy web service (http://<sharepointurl>/_vti_bin/TaxonomyClientService.asmx).
The first problem was the poor functionality of the web service like being unable to add Labels to Terms.
This cannot be fixed worked around.

Then I had to query SharePoint for a Term that contained an ampersand.
Adding the Term was not a problem when the XML was escaped properly.

string _newterm = “V&D”;

_newterm = _newterm.Replace(“&”, “&amp;”).Replace(“<“, “&lt;”).Replace(“>”, “&gt;”).Replace(“\””, “&quot;”).Replace(“‘”, “&apos;”);

But when the SharePoint is queried for a certain Term… it works slightly different.

The TermStore can be queried for example using “GetTermsByLable()”

string TermXml = SPTaxService.GetTermsByLabel(TermLabel,

1033,

StringMatchOption.ExactMatch,

10,

NewTermXml,

false);

When you send use the TaxonomyClientService.asmx, the service will not find your term, even though when you created it you used the exact same string.

The reason is that an & will be stored by SharePoint as \uFF06

So when you wanna search for a Term, make sure you replace the ampersand… like…

string XmlTerm = “<newTerms><newTerm label=\”” + _newterm.Replace(“&”, “\uFF06”) + “\” clientId=\”1\” parentTermId=\”” + Guid.Empty + “\”></newTerm></newTerms>”);

The weird thing is, that the VS2010 Debugger still will show you the &amp;
The result from SharePoint is the right one…

So …replacing the & with &amp; does not work..!