public void LendItem(string itemid, string lendby, string witnessBy) { var item = dac.GetItem(x => x._id == itemid); item.Canlend = false; item.CanSendBack = true; var lenitem = dac.GetLendItem(x => x.ItemId == item._id); LendLog newLog = new LendLog() { ActionBy = lendby, ActionDate = DateTime.UtcNow, Status = "lend", WitnessBy = witnessBy, }; var logs = lenitem.Log.ToList(); logs.Add(newLog); lenitem.Log = logs; dac.UpdateItem(item); dac.UpdtaeLendItem(lenitem); }