How i can update a managed metadata column with multiple values using CSOM

Question

I have the following code inside my remote event reciever, to create a new folder, and then populate the folder managed metadata fields with the current item (item that was added) values:-

ListItem listItem = context.Web.GetList(webrelativeurl +  "/"+i2["TemplateListUrl"]).AddItem(listItemCreationInformation);

listItem["FolderType"] = currentitem["FolderType"];
listItem["CorpType"] = currentitem["CorpType"];

now the FodlerType on both the current item and the listitem is a managed metadata column which allow single value only, while the CorpType allow multiple values. my above code will assign a value for the FolderType , but will raise this error when updating the CorpType:-

Microsoft.SharePoint.Client.ClientRequestException
HResult=0x80131500 Message=The object is not associated with an object identity or the object identity is invalid. Source= StackTrace:

any advice?

Answer 1

You need to get a TaxonomyFieldValueCollection use the SetFieldValueByValueCollection of the TaxonomyField object.

var field = item.ParentList.Fields.GetByInternalNameOrTitle("CorpType");
var corpTypeTaxField = context.CastTo<TaxonomyField>(field);
context.Load(item,i=>i[TaxKeywordFieldName]);

corpTypeTaxField.SetFieldValueByValueCollection(listItem, (TaxonomyFieldValueCollection) currentitem["CorpType"]);    

Note, this gets a lot messier if you have terms that you need to look up to construct a TaxonomyFieldValueCollection from scratch -- copying it from another item is definitely easier.

Answer 2

You can modify the code as below.

List list = context.Web.GetList(webrelativeurl + "/" + i2["TemplateListUrl"]);

Field field = list.Fields.GetByInternalNameOrTitle("CorpType");
context.Load(field);
context.ExecuteQuery();

TaxonomyField txField = context.CastTo<TaxonomyField>(field);
TaxonomyFieldValueCollection termValues = null;
string termValueString = string.Empty;
termValues = currentitem["CorpType"] as TaxonomyFieldValueCollection;
foreach (TaxonomyFieldValue tv in termValues)
{
    termValueString += tv.WssId + ";#" + tv.Label + "|" + tv.TermGuid + ";#";
}
termValueString= termValueString.Remove(termValueString.Length - 2);
termValues = new TaxonomyFieldValueCollection(context, termValueString, txField);

ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();
ListItem listItem = list.AddItem(itemCreateInfo);
listItem["FolderType"] = currentitem["FolderType"];
txField.SetFieldValueByValueCollection(listItem, termValues);
listItem.Update();
context.ExecuteQuery();