hive_ce 2.7.0

Hive Community Edition - A spiritual continuation of Hive v2

Fast, Enjoyable & Secure NoSQL Database

Hive is a lightweight and blazing fast key-value database written in pure Dart. Inspired by Bitcask.

Documentation & Samples 📖

If you need queries, multi-isolate support or links between objects check out Isar Database.

Migrating from Hive

The hive_ce package is a drop in replacement for Hive v2. Make the following replacements in your project:

pubspec.yaml

# old dependencies
dependencies:
  hive: ^2.0.0
  hive_flutter: ^1.0.0

dev_dependencies:
  hive_generator: ^1.0.0

# new dependencies
dependencies:
  hive_ce: latest
  hive_ce_flutter: latest

dev_dependencies:
  hive_ce_generator: latest

Dart files

// old imports
import 'package:hive/hive.dart';
import 'package:hive_flutter/hive_flutter.dart';

// new imports
import 'package:hive_ce/hive.dart';
import 'package:hive_ce_flutter/hive_flutter.dart';

Features

• 🚀 Cross platform: mobile, desktop, browser
• ⚡ Great performance (see benchmark)
• ❤️ Simple, powerful, & intuitive API
• 🔒 Strong encryption built in
• 🎈 NO native dependencies
• 🔋 Batteries included

Getting Started

Check out the Quick Start documentation to get started.

Usage

You can use Hive just like a map. It is not necessary to await Futures.

var box = Hive.box('myBox');

box.put('name', 'David');

var name = box.get('name');

print('Name: $name');

BoxCollections

BoxCollections are a set of boxes which can be similarly used as normal boxes, except of that they dramatically improve speed on web. They support opening and closing all boxes of a collection at once and more efficiently store data in indexed DB on web.

Aside, they also expose Transactions which can be used to speed up tremendous numbers of database transactions on web.

On dart:io platforms, there is no performance gain by BoxCollections or Transactions. Only BoxCollections might be useful for some box hierarchy and development experience.

// Create a box collection
  final collection = await BoxCollection.open(
    'MyFirstFluffyBox', // Name of your database
    {'cats', 'dogs'}, // Names of your boxes
    path: './', // Path where to store your boxes (Only used in Flutter / Dart IO)
    key: HiveCipher(), // Key to encrypt your boxes (Only used in Flutter / Dart IO)
  );

  // Open your boxes. Optional: Give it a type.
  final catsBox = collection.openBox<Map>('cats');

  // Put something in
  await catsBox.put('fluffy', {'name': 'Fluffy', 'age': 4});
  await catsBox.put('loki', {'name': 'Loki', 'age': 2});

  // Get values of type (immutable) Map?
  final loki = await catsBox.get('loki');
  print('Loki is ${loki?['age']} years old.');

  // Returns a List of values
  final cats = await catsBox.getAll(['loki', 'fluffy']);
  print(cats);

  // Returns a List<String> of all keys
  final allCatKeys = await catsBox.getAllKeys();
  print(allCatKeys);

  // Returns a Map<String, Map> with all keys and entries
  final catMap = await catsBox.getAllValues();
  print(catMap);

  // delete one or more entries
  await catsBox.delete('loki');
  await catsBox.deleteAll(['loki', 'fluffy']);

  // ...or clear the whole box at once
  await catsBox.clear();

  // Speed up write actions with transactions
  await collection.transaction(
    () async {
      await catsBox.put('fluffy', {'name': 'Fluffy', 'age': 4});
      await catsBox.put('loki', {'name': 'Loki', 'age': 2});
      // ...
    },
    boxNames: ['cats'], // By default all boxes become blocked.
    readOnly: false,
  );

Store objects

Hive not only supports primitives, lists and maps but also any Dart object you like. You need to generate a type adapter before you can store objects.

@HiveType(typeId: 0)
class Person extends HiveObject {

  @HiveField(0)
  String name;

  @HiveField(1)
  int age;
}

Add the following to your pubspec.yaml

dev_dependencies:
  build_runner: latest
  hive_ce_generator: latest

And run the following command to generate the type adapter

flutter pub run build_runner build --delete-conflicting-outputs

This will generate all of your TypeAdapters as well as a Hive extension to register them all in one go

import 'package:your_package/hive_registrar.g.dart';

void main() {
  final path = Directory.current.path;
  Hive
    ..init(path)
    ..registerAdapters();
}

Extending HiveObject is optional but it provides handy methods like save() and delete().

var box = await Hive.openBox('myBox');

var person = Person()
  ..name = 'Dave'
  ..age = 22;
box.add(person);

print(box.getAt(0)); // Dave - 22

person.age = 30;
person.save();

print(box.getAt(0)) // Dave - 30

Add fields to objects

When adding a new non-nullable field to an existing object, you need to specify a default value to ensure compatibility with existing data.

For example, consider an existing database with a Person object:

@HiveType(typeId: 0)
class Person extends HiveObject {
  Person({required this.name, required this.age});

  @HiveField(0)
  String name;

  @HiveField(1)
  int age;
}

If you want to add a balance field:

@HiveType(typeId: 0)
class Person extends HiveObject {
  Person({required this.name, required this.age, required this.balance});

  @HiveField(0)
  String name;

  @HiveField(1)
  int age;

  @HiveField(2)
  int balance;
}

Without proper handling, this change will cause null errors in the existing application when accessing the new field.

To resolve this issue, you can set a default value in the constructor (this requires hive_ce_generator 1.5.0+)

@HiveType(typeId: 0)
class Person extends HiveObject {
  Person({required this.name, required this.age, this.balance = 0});

  @HiveField(0)
  String name;

  @HiveField(1)
  int age;

  @HiveField(2)
  int balance;
}

Or specify it in the HiveField annotation:

@HiveField(2, defaultValue: 0)
int balance;

Alternatively, you can write custom migration code to handle the transition.

After modifying the schema, remember to run the build runner to generate the necessary code:

flutter pub run build_runner build --delete-conflicting-outputs

This will update your Hive adapters to reflect the changes in your object structure.

Hive ❤️ Flutter

Hive was written with Flutter in mind. It is a perfect fit if you need a lightweight datastore for your app. After adding the required dependencies and initializing Hive, you can use Hive in your project:

import 'package:hive_ce/hive.dart';
import 'package:hive_ce_flutter/hive_flutter.dart';

class SettingsPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder(
      valueListenable: Hive.box('settings').listenable(),
      builder: (context, box, widget) {
        return Switch(
          value: box.get('darkMode'),
          onChanged: (val) {
            box.put('darkMode', val);
          }
        );
      },
    );
  }
}

Boxes are cached and therefore fast enough to be used directly in the build() method of Flutter widgets.

Benchmark

1000 read iterations	1000 write iterations
SharedPreferences is on par with Hive when it comes to read performance. SQLite performs much worse.	Hive greatly outperforms SQLite and SharedPreferences when it comes to writing or deleting.

The benchmark was performed on a Oneplus 6T with Android Q. You can run the benchmark yourself.

*Take this benchmark with a grain of salt. It is very hard to compare databases objectively since they were made for different purposes.

Licence

Copyright 2019 Simon Leier

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.