Simple TODO app using Hive database in Flutter

main.dart

import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'package:hive_db_example/my_home_page.dart';
import 'package:hive_db_example/task_model.dart';
import 'package:path_provider/path_provider.dart' as path_provider;

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  final applicatonDocumentDir =
      await path_provider.getApplicationDocumentsDirectory();
  Hive.init(applicatonDocumentDir.path);
  Hive.registerAdapter(TaskAdapter());
  await Hive.openBox<Task>('TODOs');
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Simple TODO App Using Hive',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(),
    );
  }
}

my_home_page.dart

import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'package:hive_db_example/task_model.dart';
import 'package:hive_flutter/hive_flutter.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  String inputTask;

  Task _task;

  Box<Task> todosBox;

  void _addTodo(Task inputTodo) {
    todosBox.add(Task(task: inputTodo.task));
  }

  @override
  Widget build(BuildContext context) {
    // notesBox.clear();
    return Scaffold(
      appBar: AppBar(
        title: Text('Simple TODO app using Hive'),
      ),
      body: ValueListenableBuilder(
          valueListenable: Hive.box<Task>('TODOs').listenable(),
          builder: (context, Box<Task> _notesBox, _) {
            todosBox = _notesBox;
            return ListView.builder(
                itemCount: _notesBox.values.length,
                itemBuilder: (BuildContext context, int index) {
                  final todo = todosBox.getAt(index);
                  return ListTile(
                    title: Text(todo.task),
                    onLongPress: () => todosBox.deleteAt(index),
                  );
                });
          }),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _simpleDialog(),
        tooltip: 'AddNewTODOTask',
        child: Icon(Icons.add),
      ),
    );
  }

  _simpleDialog() {
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return SimpleDialog(
          title: const Text('New TODO Task'),
          children: <Widget>[
            Center(
              child: Padding(
                padding: const EdgeInsets.all(15.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: [
                    TextField(
                      decoration: InputDecoration(
                        hintText: 'TODO Task',
                        focusedBorder: OutlineInputBorder(
                          borderSide: BorderSide(
                            color: Colors.blue,
                          ),
                        ),
                        border: InputBorder.none,
                      ),
                      onChanged: (value) => inputTask = value,
                    ),
                    Padding(
                      padding: const EdgeInsets.all(15.0),
                      child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        children: [
                          FlatButton(
                            color: Colors.blue,
                            onPressed: () {
                              _task = Task(task: inputTask);
                              _addTodo(_task);
                              Navigator.pop(context);
                            },
                            child: Text('Add'),
                          ),
                          FlatButton(
                            color: Colors.blue,
                            onPressed: () => Navigator.pop(context),
                            child: Text('Cancel'),
                          )
                        ],
                      ),
                    ),
                  ],
                ),
              ),
            )
          ],
        );
      },
    );
  }

  @override
  void dispose() {
    // remove the deleted index holes/slots from database
    // to free up the space
    todosBox.compact();

    todosBox.close();
    super.dispose();
  }
}

task_model.dart

import 'package:hive/hive.dart';
 
part 'task_model.g.dart';
 
@HiveType(typeId: 0)
class Task {
  @HiveField(0)
  String task;
 
// Just an example for next attribute
// @HiveField(1)
// bool checked;
 
  Task({this.task});
}

task_model.g.dart

// GENERATED CODE - DO NOT MODIFY BY HAND
 
part of 'task_model.dart';
 
// **************************************************************************
// TypeAdapterGenerator
// **************************************************************************
 
class TaskAdapter extends TypeAdapter<Task> {
  @override
  final int typeId = 0;
 
  @override
  Task read(BinaryReader reader) {
    final numOfFields = reader.readByte();
    final fields = <int, dynamic>{
      for (int i = 0; i < numOfFields; i++) reader.readByte(): reader.read(),
    };
    return Task(
      task: fields[0] as String,
    );
  }
 
  @override
  void write(BinaryWriter writer, Task obj) {
    writer
      ..writeByte(1)
      ..writeByte(0)
      ..write(obj.task);
  }
 
  @override
  int get hashCode => typeId.hashCode;
 
  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is TaskAdapter &&
          runtimeType == other.runtimeType &&
          typeId == other.typeId;
}