I am creating a simple app for transaction using hive..

i am success to add and fetch all transaction and assign to controller’s list but how to update local storage of hive, bcz i am ussing add method to add data in box, and add does generate id its own way..so how to get it to update specific key’s value

class TransactionController extends GetxController {
  static TransactionController get instance=>Get.find();
  RxList<TransactionModel> _allTransactions = <TransactionModel>[].obs;
  List<TransactionModel> get getAllTransactions=>_allTransactions;
  RxBool isLoading=false.obs;
  Box<TransactionModel> transactionbox = Hive.box('MyBox');
  
  @override
  void onInit() {
    // TODO: implement onInit
    super.onInit();
    fetchData();
  }

  void fetchData() async {
    try{
      isLoading.value=true;
      final data=transactionbox.values.toList();
      if(data!=null)
        {
          _allTransactions.assignAll(data);
        }
     
      isLoading.value=false;
    }catch(e){
      print('E R R O R'+e.toString());
      isLoading.value=false;
    }
  }

   

  void addTransaction(TransactionModel transactionModel)
  {
    _allTransactions.add(transactionModel);
    _allTransactions.refresh();
    transactionbox.add(transactionModel);
   
  }

  void update(TransactionModel transactionModel){


   transactionbox.put(key,transactionModel);
   //how to get key of this transactonModel bcz add method generate its own..
  }
}