Introducing Nitrite for Flutter : An embedded NoSQL database for Flutter

Anindya Chatterjee — Sat, 20 Jan 2024 07:48:20 +0000

NOsql Object (NO2 a.k.a. Nitrite) is a server-less, embedded, and self-contained NoSQL database. It is an open-source project that provides a simple API for persistent data storage. Nitrite database is designed to be lightweight, fast, and easy to use. Apart from Flutter it is available in Java and Kotlin as well.

Nitrite database can be used in various scenarios where a lightweight, embedded, and server-less NoSQL database is required. Some of the use cases for Nitrite database are:

Mobile and desktop applications
IoT devices and sensors
Web applications and APIs
Prototyping and testing
Data caching and synchronization
Data analysis and reporting

Nitrite database is designed to be simple and easy to use, making it an ideal choice for Flutter applications. Nitrite is written in pure Dart without any native dependencies.

✨ Features

Embedded, server-less
Simple API
Document-oriented
Schema-less document collection and object repository
Extensible storage engines
Indexing and full-text search
Simple query API
In-memory and file-based store
Transaction support
Schema migration support
Encryption support

Nitrite also comes with a well written documentation with lots of examples to get you started.

🚀 Getting Started

Nitrite is a pure Dart database. It does not depend on any native library. So it can be used in any platform where Dart is supported. It is a server-less embedded database ideal for desktop, mobile, or web applications. It is written in pure Dart and runs in Flutter, Dart VM, and the browser. To use Nitrite in your project, add the following package to your package:

dart pub add nitrite

By design, Nitrite is modular and extensible. It has a core module which provides all the basic features. Additional features like persistent storage, spatial indexing, encryption etc. are available as separate modules. You only need to add the modules you need.

As for example, if you want to use Nitrite with persistent storage, add the following additional dependency in your project:

dart pub add nitrite_hive_adapter

More on the module API can be found here.

✍️ Usage

To create a new database or open an existing database, use the builder API to create a database instance:

import 'package:nitrite/nitrite.dart';

var db = await Nitrite.builder()
    .openOrCreate(username: 'user', password: 'pass123');

By default, Nitrite uses in-memory storage. To use persistent storage, load a persistent storage module. Nitrite provides a persistent storage module based on Hive.

// create a hive backed storage module
var storeModule = HiveModule.withConfig()
    .crashRecovery(true)
    .path('$dbDir/db')
    .build();


// initialization using builder
var db = await Nitrite.builder()
    .loadModule(storeModule)
    .openOrCreate(username: 'user', password: 'pass123');

🗂️ Nitrite Collection

Nitrite stores data as a collection of documents. A Document is a simple key-value pair. To store a document in a collection, use the following code:

var coll = await db.collection('test');

// create a document
var document = createDocument("firstName", "John")
    .put("phone", ["212-555-1234", "646-555-4567"]);

// insert the document
await coll.insert(document);

More on the NitriteCollection is available here.

📦 Object Repository

Nitrite also provides ObjectRepository which is nothing but a abstraction over NitriteCollection to store Dart objects. Nitrite uses converters to map a Dart object to a document and stores it in a collection.

var repo = await db.getRepository<Person>();

// create a person object
var person = Person()
    ..firstName = 'John'
    ..lastName = 'Doe'
    ..age = 30
    ..address = Address()
      ..street = '21 2nd Street'
      ..city = 'New York'
      ..state = 'NY'
      ..country = 'USA'
      ..zip = '10021';

// insert the person object
await repo.insert(person);

You can either write your own converter or use the Nitrite’s code generator to generate the converter for you. To use the code generator, add the following dev dependencies in your project:

dart pub add nitrite_generator --dev
dart pub add build_runner --dev

More on ObjectRepository can be found in guide here.

📇 Indexing

Nitrite supports indexing on single or multiple fields to optimize the performance of a database by minimizing the number of disk accesses required when a query is processed. It supports following types of indexes:

Unique Index
Non-Unique Index
Full-text Index
Spatial Index via spatial module

You can even create your own custom index using the Module API. To create an index on a field,

// create a non-unique index on field 'firstName'
await coll.createIndex(['firstName'], indexOptions(IndexType.nonUnique));

// create a full-text index on field 'note'
await coll.createIndex(['note'], indexOptions(IndexType.fullText));

// create a unique index on field 'phone' and 'email'
await coll.createIndex(['phone', 'email']);

🔍 Query

Nitrite provides a fluent API for find operation. It also provides a simple query DSL based on Dart language features like extension methods and operator overloading.

// find all documents where firstName is 'John'
var cursor = coll.find(filter: where('firstName').eq('John'));

// find all documents where firstName is 'John' and age is greater than 25
var cursor = coll.find(filter: 'name'.eq('John') & 'age' > 18);

Extensive details about all types of Filters and example can be found here in the guide.

🤝 Transaction

Nitrite has support for transaction on NitriteCollection and ObjectRepository. Transactions can be used as follows:

var session = db.createSession();

await session.executeTransaction((transaction) async {
  var collection = await transaction.getCollection("test");
  await collection.insert(doc1);
}, rollbackFor: [NitriteException]);

How to predict action by processing multiple free texts in java

Anindya Chatterjee — Fri, 20 Dec 2019 08:22:16 +0000

How to predict action by processing multiple free texts in java

Dec 19 '19 Comments: 3 Answers: 0

I have a multi-column data set as follows

Id      Summary        Component       Description      Labels             Action

id1     free-text-11   free-text-12    free-text-13     label1, label2     action1
id2     free-text-11   free-text-22    free-text-23     label2, label3     action2

... so on

Here Summary, Component, Description contains user provided free text in english. Labels and Action columns contains system…

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Introducing Nitrite for Flutter : An embedded NoSQL database for Flutter

✨ Features

🚀 Getting Started

✍️ Usage

🗂️ Nitrite Collection

📦 Object Repository

📇 Indexing

🔍 Query

🤝 Transaction

How to predict action by processing multiple free texts in java

How to predict action by processing multiple free texts in java