TaxonomyField not updating

Question

I have a little function that updates a taxonomy field on a listitem. It does work when I call it from the SharePoint site, but If I call it from a WCF service (built on top of SharePoint's WCF factory) it does not updates the field (and it does not throws an exception or anything) Any ideas?

[UPDATE]

Here's some sample code so you can see what I'm doing, lets start with the service implementation:

    [BasicHttpBindingServiceMetadataExchangeEndpointAttribute]
    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)]
    [ServiceBehavior(IncludeExceptionDetailInFaults = true)]    
    public class PQRSService : IPQRSService
    {
        public void CancelPQRRequest(Guid libraryID, int pqrID)
        {
            PQRSBLL.CancelPQRRequest(libraryID, pqrID);
        }
    }
}

Now, the Cancel pqr request:

public static void CancelPQRRequest(Guid libraryID, int pqrID)
        {
            SPList library = SPContext.Current.Web.Lists.GetList(libraryID, false);
            SPListItem request = library.GetItemById(pqrID);
            SPFolder requestAsociatedFolder = request.Folder;

            SPContext.Current.Site.AllowUnsafeUpdates = true;
            SPContext.Current.Web.AllowUnsafeUpdates = true;

            MarkPQRAsCancelled(ref request);
            LogCancellation(ref requestAsociatedFolder);
            if (IsRequestInRecord(ref request))
            {
                string recordID = RemoveRequestFromRecord(ref request);
                UpdateRecordInformation(recordID, request[CustomSiteColumns.FIELD_DOCSET_UNIQUE_ID].ToString());
            }
            string newUrl = MovePQRToCancelledPQRLibrary(ref requestAsociatedFolder);
            SetPQRContentType(newUrl);

            SPContext.Current.Site.AllowUnsafeUpdates = false;
            SPContext.Current.Web.AllowUnsafeUpdates = false;
        }

Now the MarkPQRAsCancelled, which is the place where the "magic happens"

private static void MarkPQRAsCancelled(ref SPListItem request)
        {
            request[CustomSiteColumns.FIELD_DOCUMENT_STATUS] = TermStoreHelper.GetTaxonomyFieldByTerm(GlobalConstants.METADATA_GROUP_NAME, GlobalConstants.METADATA_TERM_STATUS, GlobalConstants.METADATA_TERM_STATUS_ANULADO);
            request[CustomSiteColumns.FIELD_CURRENT_ACTION] = "MoveTo";
            request.Update();
        }

Let's keep going on...

public static TaxonomyFieldValue GetTaxonomyFieldByTerm(string taxonomyGroupName, string taxonomyTermSet, string taxonomyTerm)
        {

            var taxonomyTermS = GetTermSetByName(taxonomyGroupName, taxonomyTermSet);
            if (taxonomyTermS == null) throw new Exception("Termset:" + taxonomyTermSet + " does not exists");
            var term = taxonomyTermS.Terms.Where(c => string.Compare(c.Name, taxonomyTerm, true) == 0).FirstOrDefault();
            if (term == null) throw new Exception("Term:" + taxonomyTerm + " does not exist");
            TaxonomyFieldValue val = new TaxonomyFieldValue(string.Empty);
            val.PopulateFromLabelGuidPair(taxonomyTerm + "|" + term.Id);
            val.WssId = -1;

            return val;

        }

And on...

public static TermSet GetTermSetByName(string taxonomyGroupName, string taxonomyTermSet)
        {
            var taxonomyGroup = GetTaxonomyGroupByName(taxonomyGroupName);
            if (taxonomyGroup == null) throw new Exception("Taxonomy group:" + taxonomyGroupName + " does not exits");
            return taxonomyGroup.TermSets.Where(c => string.Compare(c.Name, taxonomyTermSet, true) == 0).FirstOrDefault();
        }

And on...

public static Group GetTaxonomyGroupByName(string GroupName)
        {
            var site = SPContext.Current.Site;
            var session = new TaxonomySession(site);
            return session.TermStores[ConfigurationHelper.GetInstance().ConfigItems[GlobalConstants.METADATA_SERVICE_NAME]].Groups.Where(c => string.Compare(c.Name, GroupName, true) == 0).FirstOrDefault();
        }

Well that's pretty much everything, again, any help would be appreciated

Answer 1

[update]

You are almost there, at first I thought you where referencing the 2013 namespace which does exist, it just doesn't work, now I know a bit more I am 90% sure you can get around your issue with the following. I know I know it might not seem to be what you want at first, but I assure you it is.

I see what you are doing now and I think this will work for you.

WssID = -1 = This term hasn't been used yet.

Setting Managed Metadata via CSOM This explains the situation in detail, the basics is the handler isn't there unless you are doing it locally. Remember all Managed-Metadata fields are, are extended lookup fields. This will explain pretty much everything you need to know. If you want to update MM fields remotely, this is the way to go.

Some further reading if the WssID isn't created

note: Microsoft.SharePoint.Taxonomy.WebServices.TaxonomyClientService Is only for SharePoint 2013.