Set Lookup field value

设置Lookup字段

var categorySet = Categories.Split(';');
List<FieldLookupValue> branchLookupValueList = new List<FieldLookupValue>();
List<Categorie> _list = new List<Categorie>();
_list = listCategories.Where(a => categorySet.Contains(a.Title)).ToList();
foreach (var item in _list)
{
    FieldLookupValue LookupColBranch = new FieldLookupValue();
    LookupColBranch.LookupId = Convert.ToInt32(item.ID);
    branchLookupValueList.Add(LookupColBranch);
}
if (branchLookupValueList.Count > 0)
{
    listItem["Categories"] = branchLookupValueList;
}
listItem.update();