Flutter hive

Hive CE NoSQL Database Guide

Goal

Implement high-performance NoSQL object storage using Hive CE (Community Edition). Hive offers blazing-fast synchronous operations, custom type adapters, and lazy loading for efficient local data persistence.

Process

Phase 1: Install Dependencies

dependencies:
  hive_ce: ^2.19.3
  hive_ce_flutter: ^2.3.4

dev_dependencies:
  hive_ce_generator: ^1.11.1
  build_runner: ^2.14.1

Phase 2: Initialize Hive

import 'package:hive_ce_flutter/hive_ce_flutter.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  
  await Hive.initFlutter();
  
  // Register adapters
  Hive.registerAdapter(UserAdapter());
  Hive.registerAdapter(TodoAdapter());
  
  // Open boxes
  await Hive.openBox<User>('users');
  await Hive.openBox<Todo>('todos');
  
  runApp(MyApp());
}

Phase 3: Define Models with TypeAdapters

Using Code Generation (Recommended):

import 'package:hive_ce/hive.dart';

part 'user.g.dart';

@HiveType(typeId: 0)
class User extends HiveObject {
  @HiveField(0)
  final String id;
  
  @HiveField(1)
  final String name;
  
  @HiveField(2)
  final String email;
  
  @HiveField(3)
  final DateTime createdAt;
  
  User({
    required this.id,
    required this.name,
    required this.email,
    required this.createdAt,
  });
}

// Generate adapter: flutter pub run build_runner build

Manual TypeAdapter:

class UserAdapter extends TypeAdapter<User> {
  @override
  final int typeId = 0;

  @override
  User read(BinaryReader reader) {
    return User(
      id: reader.readString(),
      name: reader.readString(),
      email: reader.readString(),
      createdAt: DateTime.fromMillisecondsSinceEpoch(reader.readInt()),
    );
  }

  @override
  void write(BinaryWriter writer, User obj) {
    writer.writeString(obj.id);
    writer.writeString(obj.name);
    writer.writeString(obj.email);
    writer.writeInt(obj.createdAt.millisecondsSinceEpoch);
  }
}

Phase 4: CRUD Operations

Create/Update:

final box = Hive.box<User>('users');

// Add with auto-key
await box.add(User(id: '1', name: 'John', email: '[email protected]', createdAt: DateTime.now()));

// Put with custom key
await box.put('user_1', user);

// Update (if model extends HiveObject)
user.name = 'Jane';
await user.save();

Read:

// Get by key
final user = box.get('user_1');

// Get all values
final allUsers = box.values.toList();

// Filter
final activeUsers = box.values.where((u) => u.isActive).toList();

// Get at index
final firstUser = box.getAt(0);

Delete:

// Delete by key
await box.delete('user_1');

// Delete at index
await box.deleteAt(0);

// Delete if model extends HiveObject
await user.delete();

// Clear all
await box.clear();

Phase 5: Advanced Patterns

Lazy Boxes (for large data):

// Open lazy box (loads data on demand)
final lazyBox = await Hive.openLazyBox<User>('users_lazy');

// Async get (only loads when accessed)
final user = await lazyBox.get('user_1');

Encrypted Boxes:

import 'package:hive_ce/hive.dart';
import 'dart:convert';
import 'dart:typed_data';

final key = Hive.generateSecureKey(); // Store this securely!

final encryptedBox = await Hive.openBox<User>(
  'secure_users',
  encryptionCipher: HiveAesCipher(key),
);

Reactive Listening:

// Listen to box changes
box.watch().listen((event) {
  print('Box changed: ${event.key}');
  if (event.deleted) {
    print('Item deleted');
  } else {
    print('Item added/updated: ${event.value}');
  }
});

// Listen to specific key
box.watch(key: 'user_1').listen((event) {
  print('User 1 updated: ${event.value}');
});

Compaction (reduce file size):

// Compact box to reclaim space
await box.compact();

// Auto-compact on close
await box.close();

Phase 6: Integration with State Management

With Riverpod:

final userBoxProvider = Provider<Box<User>>((ref) {
  return Hive.box<User>('users');
});

final usersProvider = StreamProvider<List<User>>((ref) {
  final box = ref.watch(userBoxProvider);
  return box.watch().map((_) => box.values.toList());
});

// Usage in widget
final users = ref.watch(usersProvider);
users.when(
  data: (list) => ListView(children: list.map((u) => UserTile(u)).toList()),
  loading: () => CircularProgressIndicator(),
  error: (e, _) => Text('Error: $e'),
);

---

Constraints

• TypeId Uniqueness: TypeIds must be unique across all models (0-223 for user types).
• Schema Evolution: Adding fields is safe. Removing fields requires migration logic.
• Synchronous by Default: Most operations are sync. Use lazy boxes for large data.
• No Relations: Hive is NoSQL. Store object references (IDs) manually.
• Close Boxes: Always close boxes when no longer needed to free resources.
• Backup Key: For encrypted boxes, ALWAYS backup the encryption key securely.