How to use CSOM TermSet.GetTerms method? Receiving strange null error

Question

I have a piece of code in which I want to check if a specific Term is available within a TermSet. The TermSet is quite large, so getting all Terms is no option here.

My code looks like this:

Getting the correct TermSet:

using (ClientContext cc = _clientContext)
{
    TaxonomySession session = TaxonomySession.GetTaxonomySession(_clientContext);
    cc.Load(session, s => s.TermStores);
    cc.ExecuteQuery();
    TermStore termStore = session.TermStores.GetByName(TERM_STORE_NAME);
    cc.Load(termStore, store => store.Groups
        .Where(group => group.Name == TERM_GROUP_NAME)
        .Include(group => group.TermSets
            .Where(termSet => termSet.Name == TERM_SET_NAME)));
    cc.ExecuteQuery();

    _termSet = termStore.Groups[0].TermSets[0];
}

Checking if the Term exists within the TermSet:

public bool TermAvailableInTermSet(LabelMatchInformation labelparam)
{
    LabelMatchInformation label = new LabelMatchInformation(_clientContext)
    {
        TrimUnavailable = false,
        DefaultLabelOnly = false,
        StringMatchOption = StringMatchOption.ExactMatch,
        Lcid = 1033,
    };

    label.TermLabel = "Test";

    TermCollection terms = LocationTermSet.GetTerms(label); 
    _clientContext.Load(label);
    _clientContext.Load(terms);
    _clientContext.ExecuteQuery();

    return (terms != null && terms.Count > 0);
}

With this code everything runs like expected until I Execute the query with GetTerms. A really peculiar error is returned: Value cannot be null.\r\nParameter name: labelMatchInformation.TermLabel. So I obviously checked if I hadn't forgotten to set the TermLabelvariable. But the variable seemed fine: What am I missing here? I assume this is the right way to use GetTerms, it also seems like the only option for me here.

Answer 1

Here is my sample test code which works in my local, hope it would help you.

using (var ctx = new ClientContext("http://sp:12001/"))
            {
                TaxonomySession taxonomySession = TaxonomySession.GetTaxonomySession(ctx);
                //taxonomySession.UpdateCache();
                TermStore termStore = taxonomySession.GetDefaultSiteCollectionTermStore();
                ctx.Load(termStore,
                    termStoreArg => termStoreArg.WorkingLanguage,
                    termStoreArg => termStoreArg.Id,
                    termStoreArg => termStoreArg.Groups.Include(
                        groupArg => groupArg.Id,
                        groupArg => groupArg.Name
                    )
                );
                ctx.ExecuteQuery();


                TermSet termSet = termStore.GetTermSet(new Guid("2bdf0a4e-9ff8-4db0-9f43-a9ea809d1b18"));
                ctx.Load(termSet);
                ctx.ExecuteQuery();
                //search for the Term to see if it exists
                LabelMatchInformation termQuery = new LabelMatchInformation(ctx)
                {
                    TermLabel = "Developer Members",                   
                    TrimUnavailable = false
                };
                var matchingTerms = termSet.GetTerms(termQuery);
                ctx.Load(matchingTerms);
                ctx.ExecuteQuery();

                if (matchingTerms.Count <1)
                {
                    Console.WriteLine("not found");
                }
                else
                {
                    Console.WriteLine(matchingTerms.Count);
                }

                Console.ReadKey();
            }