sharepoint lookup字段的读取与赋值

var columnFieldValue = oListItem.get_item("columnName");
var lookupValue = columnFieldValue.get_lookupValue();
var lookupId = columnFieldValue.get_lookupId();

var lookupValue = new SP.FieldLookupValue();
lookupValue.set_lookupId($("select[title=‘车辆资源(Resources) selected values‘] option")[0].value);
listItem.set_item(‘lookupColumn‘,lookupValue);