ذخیره کردن اطلاعات در فلاتر با دیتابیس Hive

hive: ^1.4.1+1
provider: ^4.3.1
path_provider: ^1.6.5
hive_generator: ^0.5.0

import 'package:hive/hive.dart';
import 'package:path_provider/path_provider.dart' as pathProvider;

Future<void> main() async {
  Directory directory = await pathProvider.getApplicationDocumentsDirectory();
  Hive.init(directory.path);

  runApp(MyApp());
}

import 'package:hive/hive.dart';

part 'inventory_model.g.dart';

@HiveType()
class Inventory {
  @HiveField(0)
  final String name;

  @HiveField(1)
  final String description;

  Inventory({this.name, this.description});
}

$ flutter packages pub run build_runner build

@override
int get typeId => 0;

Hive.registerAdapter(InventoryAdapter());
runApp(MyApp());

addItem(Inventory item) async {
    var box = await Hive.openBox<Inventory>('inventory');

    box.add(item);

    notifyListeners();
  }

inputItemDialog(BuildContext context, String action, [int index]) {
    var inventoryDb = Provider.of<HomeModel>(context, listen: false);

    showDialog(
      context: context,
      builder: (context) {
        return Dialog(
          child: Container(
            padding: EdgeInsets.only(
              left: 15,
              right: 15,
              top: 40,
            ),
            height: 45.height,
            child: SingleChildScrollView(
              child: Form(
                key: _formKey,
                child: Column(
                  children: <Widget>[
                    Text(
                      action == 'add' ? 'Add Item' : 'Update Item',
                      style: TextStyle(
                        fontWeight: FontWeight.bold,
                        fontSize: 20,
                      ),
                    ),
                    SizedBox(
                      height: 10,
                    ),
                    TextFormField(
                      controller: nameController,
                      validator: (value) {
                        if (value.isEmpty) {
                          return 'Item name cannot be empty';
                        }
                        return null;
                      },
                      decoration: InputDecoration(
                        labelText: 'Item name',
                      ),
                    ),
                    SizedBox(
                      height: 40,
                    ),
                    TextFormField(
                      controller: descriptionController,
                      validator: (value) {
                        if (value.isEmpty) {
                          return 'Item description cannot be empty';
                        }
                        return null;
                      },
                      decoration: InputDecoration(
                        labelText: 'Item description',
                      ),
                    ),
                    SizedBox(
                      height: 40,
                    ),
                    RaisedButton(
                      onPressed: () async {
                        if (_formKey.currentState.validate()) {
                          if (action == 'add') {
                            await inventoryDb.addItem(Inventory(
                              name: nameController.text,
                              description: descriptionController.text,
                            ));
                          } else {
                            
                          }

                          nameController.clear();
                          descriptionController.clear();

                          inventoryDb.getInventory();

                          Navigator.pop(context);
                        }
                      },
                      color: Colors.green[600],
                      child: Text(
                        action == 'add' ? 'Add' : 'update',
                        style: TextStyle(
                          fontSize: 16,
                          color: Colors.white,
                        ),
                      ),
                    ),
                    SizedBox(
                      height: 20,
                    )
                  ],
                ),
              ),
            ),
          ),
        );
      },
    );
  }

List _inventoryList = <Inventory>[];
List get inventoryList => _inventoryList;

getItem() async {
    final box = await Hive.openBox<Inventory>('inventory');

    _inventoryList = box.values.toList();

    notifyListeners();
 }

ListView.builder(
     itemCount: model.inventoryList.length,
     itemBuilder: (context, index) {
       Inventory inv = model.inventoryList[index];
       return Container(
          margin: EdgeInsets.symmetric(
          vertical: 2.height,
          horizontal: 4.5.width,
         ),
          height: 13.height,
          decoration: BoxDecoration(
          color: Colors.white,
          ),
          child: Row(
            children: <Widget>[
              Container(
                margin: EdgeInsets.only(left: 2.width),
                width: 16.width,
                decoration: BoxDecoration(
                color: Colors.green[600],
                shape: BoxShape.circle,
                ),
                child: Center(
                  child: Icon(
                     Icons.home,
                     color: Colors.white,
                        ),
                      ),
                    ),
                    Padding(
                     padding: EdgeInsets.symmetric(
                     vertical: 3.height,
                     horizontal: 3.width,
                     ),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                         children: <Widget>[
                            Text(
                             inv.name,
                              style: TextStyle(
                               color: Colors.green[600],
                               fontWeight: FontWeight.w600,
                               fontSize: 4.5.text,
                                 ),
                               ),
                               SizedBox(
                                height: 1.height,
                               ),
                                  Text(
                                    inv.description,
                                    style: TextStyle(
                                      color: Colors.grey,
                                      fontSize: 4.text,
                                    ),
                                  ),
                                ],
                              ),
                            ),
                            Padding(
                              padding: EdgeInsets.only(left: 8.width),
                              child: PopupMenuButton(
                                onSelected: (item) {
                                  switch (item) {
                                    case 'update':
                                      nameController.text = inv.name;
                                      descriptionController.text =
                                          inv.description;

                                      inputItemDialog(context, 'update', index);
                                      break;
                                    case 'delete':
                                      model.deleteAt(index);
                                  }
                                },
                                itemBuilder: (context) {
                                  return [
                                    PopupMenuItem(
                                      value: 'update',
                                      child: Text('Update'),
                                    ),
                                    PopupMenuItem(
                                      value: 'delete',
                                      child: Text('Delete'),
                                    ),
                                  ];
                                },
                              ),
                            ),
                          ],
                        ),
                      );
                    },
                  )

updateItem(int index, Inventory inventory) {
    final box = Hive.box<Inventory>('inventory');

    box.putAt(index, inventory);

    notifyListeners();
  }

deleteItem(int index) {
    final box = Hive.box<Inventory>(_inventoryBox);

    box.deleteAt(index);

    getInventory();

    notifyListeners();
  }

final lazyBox = await Hive.openLazyBox('name');

var value = await lazyBox.get('key');