Taxonomy Filed Issue while Copying Document Library Item Using CSOM in Sharepoint Online

Question

I am trying to Copy a Document having the Managed Metadata(Termsets) fields from one site collection to another site collection in SharePoint online using CSOM. The Managed Metadata Fields are there in both the Document libraries with different Internal names but with same display name. The Columns names are shown in below image. After Copying the document only Topic filed data is copied without any additional coding.

So I tried the below code to copy Managed Metadata(Termsets) fields after Uploading the file with internals names but the fields are not updating.

foreach (var stritem in Taxonomyfiledarray)
    {
    TaxonomyFieldValueCollection sourceValue = SourcelistItem[stritem.Source] as TaxonomyFieldValueCollection; 
    string[] termValuesarrary;
    List<string> termValues = new List<string>();
    foreach (TaxonomyFieldValue taxProductFieldValue in sourceValue)
    {
     termValues.Add(taxProductFieldValue.Label + "|" + taxProductFieldValue.TermGuid);
    }
    termValuesarrary = termValues.ToArray();
    string termValuesstring = string.Join(";", termValuesarrary);
    itemToCreate[stritem.Destination] = termValuesstring;
    }
    itemToCreate.Update();

Any Suggestion please..

Answer 1

With assumption that both of the field use same TermSet, ExecuteQuery() is also called after this, try modified code:

foreach (var stritem in Taxonomyfiledarray)
{
TaxonomyFieldValueCollection sourceValue = SourcelistItem[stritem.Source] as TaxonomyFieldValueCollection; 
string[] termValuesarrary;
List<string> termValues = new List<string>();
foreach (TaxonomyFieldValue taxProductFieldValue in sourceValue)
{
 termValues.Add("-1;#" + taxProductFieldValue.Label + "|" + taxProductFieldValue.TermGuid);
}
termValuesarrary = termValues.ToArray();
string termValuesstring = string.Join(";#", termValuesarrary);
itemToCreate[stritem.Destination] = termValuesstring;
}
itemToCreate.Update();

Answer 2

@Alok Kumar Gupta: Thanks for you guidance. Your guidance and the linkSetting a Managed Metadata Field with the Client Object Model driven me to fix the issue.

                 foreach (var stritem in Taxonomyfiledarray)
                    {
                        try
                        {

                            TaxonomyFieldValueCollection newtermValues = null;
                            Field field = fields.GetByInternalNameOrTitle(stritem.Destination);
                            destinationContext.Load(field);
                            destinationContext.ExecuteQuery();
                            TaxonomyField txField = destinationContext.CastTo<TaxonomyField>(field);
                            if (txField.AllowMultipleValues)
                            {
                                TaxonomyFieldValueCollection sourceValue = SourcelistItem[stritem.Source] as TaxonomyFieldValueCollection;
                                string[] termValuesarrary;
                                List<string> termValues = new List<string>();
                                foreach (TaxonomyFieldValue taxProductFieldValue in sourceValue)
                                {
                                    // termValues.Add(taxProductFieldValue.Label + "|" + taxProductFieldValue.TermGuid);
                                    termValues.Add("-1;#" + taxProductFieldValue.Label + "|" + taxProductFieldValue.TermGuid);
                                }
                                termValuesarrary = termValues.ToArray();
                                string termValuesstring = string.Join(";#", termValuesarrary);
                                newtermValues = new TaxonomyFieldValueCollection(destinationContext, termValuesstring, txField);
                                txField.SetFieldValueByValueCollection(itemToCreate, newtermValues);
                                itemToCreate.Update();
                                destinationContext.Load(itemToCreate);
                                destinationContext.ExecuteQuery();
                            }

                        }
                        catch (Exception ex)
                        {
                            lbl_Error.Text = ex.Message.ToString();
                        }
                    }