How to Save Manged Metadata value in List using JSOM or REST...?

Question

As i have understand it by googling a litle, that its not posible to use REST for Taxonomy fields ? I was not able to update my list doing it by http REST . But it should be posible with JSOM.

How can I save a managed metadata value in my SP.List? I have a list with one MMD column which I want to update.

My code looks like:

  $scope.saveProsessConnection = function (propertyName) {
        var taxPickerIndex = $("#taxPickerOpenSingle").val();
        console.log(taxPickerIndex);
        var result = $.parseJSON(taxPickerIndex);
        console.log(result);
        var listTitle = "GNTiles";
        var taxFieldName = "Prosess";
        var termGUID = result[0].Id;
        var termLabel = result[0].Name;
        console.log(termGUID);
        console.log(result);

        var context = new SP.ClientContext(appWebUrl);
        var list = context.get_web().get_lists().getByTitle(listTitle);
        var item = list.getItemById(tileId);
        //console.log('Item Id: '+item.id);

        var termValue = "-1" + ";#" + termLabel + "|" + termGUID;
        item.set_item(taxFieldName, termValue);
        item.update();


        context.load(item);
        context.executeQueryAsync(onSuccess, onFailure);


        function onSuccess() {
            //retriveListItem(); 
            console.log("Success!!")
        }

        function onFailure(sender, args) {
            console.log('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
        }
    }  

And my data looks like :

[{"Id":"e0a1f57a-6746-4ecc-b119-47f2ff80a1ea","Name":"L3-2 Forbedringsprosess","PathOfTerm":"L3 Lede og forbedre;L3-2 Forbedringsprosess","Children":[],"Level":1,"RawTerm":null}] 

The error iam getting is:

Request failed. Unexpected response data from server. null

Answer 1

Below snippet can be used to update MMD field

var termValue = "-1;#" + termLabel + "|" + termGUID;
item.set_item("Process", termValue);
item.update();

Answer 2

Here is how i resolved my case with updating a List Item with Managed Metadata Column.

        function execRequest() {
        var taxPickerIndex = $("#taxPickerOpenSingle").val();
        var result = $.parseJSON(taxPickerIndex);
        var listTitle = "GNTiles";
        var taxFieldName = "Process";
        var termId = result[0].Id;
        var term = result[0].Name;
        console.log("Term ID: " + termId);
        console.log(result);

        var context = new SP.ClientContext(_spPageContextInfo.siteAbsoluteUrl);
        var list = context.get_web().get_lists().getByTitle(listTitle);
        var item = list.getItemById(tileId);

        var field = list.get_fields().getByInternalNameOrTitle("Prosess");
        var txField = context.castTo(field, SP.Taxonomy.TaxonomyField);

        context.load(field);
        context.load(txField);

        context.executeQueryAsync(function () {
            //Get the term set ID  
           // var termSetId = txField.get_termSetId().toString();
            var taxSession = SP.Taxonomy.TaxonomySession.getTaxonomySession(context);
            var termStore = taxSession.getDefaultSiteCollectionTermStore();
            var termSet = termStore.getTermSet(termSetId);

            // Get the matching terms based on names  
            var lmi = new SP.Taxonomy.LabelMatchInformation(context);
            lmi.set_lcid(1033);
            lmi.set_trimUnavailable(true);
            lmi.set_termLabel("UI Developer");

            var termMatches = termSet.getTerms(lmi);
            context.load(termMatches);
            context.executeQueryAsync(function () {  
                var termFieldValue = new SP.Taxonomy.TaxonomyFieldValue();
                termFieldValue.set_label(term);
                termFieldValue.set_termGuid(termId);
                termFieldValue.set_wssId(-1);
                txField.setFieldValueByValue(item, termFieldValue);
                item.update();

                context.executeQueryAsync(function () {
                    console.log('Item Added');
                }, function (sender, args) {
                    console.log(args.get_message() + '\n' + args.get_stackTrace());
                });
             }, function (sender, args) {  
                console.log(args.get_message() + '\n' + args.get_stackTrace());  
             });

        }, function (sender, args) {
            console.log(args.get_message());
        });

    }