sequelize

What is sequelize?

Sequelize is a promise-based Node.js ORM (Object-Relational Mapping) library for Postgres, MySQL, MariaDB, SQLite, and Microsoft SQL Server. It features solid transaction support, relations, eager and lazy loading, read replication and more. Sequelize follows the Active Record paradigm and allows developers to define models and their relationships in a way that abstracts database access, making it easier to maintain and evolve the application codebase.

What are sequelize's main functionalities?

Model Definition

This feature allows you to define models in Sequelize, which represent tables in the database. Each model can have various attributes and their respective data types.

const User = sequelize.define('user', { username: Sequelize.STRING, birthday: Sequelize.DATE });

CRUD Operations

Sequelize provides methods for creating, reading, updating, and deleting records in the database, which correspond to the CRUD operations.

User.create({ username: 'alice', birthday: new Date(1986, 6, 20) }); User.findAll(); User.update({ username: 'alicejr' }, { where: { id: 1 } }); User.destroy({ where: { id: 1 } });

Associations

This feature allows you to define associations between models. For example, a user can have many posts, and a post belongs to a user.

User.hasMany(Post); Post.belongsTo(User);

Transactions

Sequelize supports transactions which allow you to execute multiple queries in an atomic way, ensuring data integrity.

sequelize.transaction(transaction => { return User.create({ username: 'bob' }, { transaction }); });

Migrations

Sequelize has a migration tool that allows you to define changes to the database schema, which can be applied and rolled back programmatically.

module.exports = { up: (queryInterface, Sequelize) => { return queryInterface.createTable('users', { id: { allowNull: false, autoIncrement: true, primaryKey: true, type: Sequelize.INTEGER }, username: { type: Sequelize.STRING } }); }, down: (queryInterface, Sequelize) => { return queryInterface.dropTable('users'); } };

Other packages similar to sequelize

mongoose

Mongoose is an ODM (Object Data Modeling) library for MongoDB and Node.js. It manages relationships between data, provides schema validation, and is used to translate between objects in code and the representation of those objects in MongoDB. Compared to Sequelize, Mongoose is specific to MongoDB, whereas Sequelize supports multiple SQL databases.

typeorm

TypeORM is an ORM that can run in Node.js and be used with TypeScript and JavaScript (ES5, ES6, ES7, ES8). It supports the Data Mapper pattern, unlike Sequelize which is more Active Record. TypeORM is highly influenced by other ORMs, such as Hibernate, Doctrine, and Entity Framework.

knex

Knex.js is a SQL query builder for Postgres, MSSQL, MySQL, MariaDB, SQLite3, Oracle, and Amazon Redshift, designed to be flexible, portable, and fun to use. It does not provide full ORM capabilities but allows you to build and run SQL queries in a more programmatic and database-agnostic way. It is often used with objection.js, which is an ORM built on top of Knex.

bookshelf

Bookshelf.js is a JavaScript ORM for Node.js, built on the Knex SQL query builder. It features transaction support, eager/nested-eager relation loading, and polymorphic associations. Bookshelf follows a somewhat similar pattern to Sequelize but is built on top of Knex, which gives it a different flavor in terms of query building.

README

Sequelize

Sequelize is an easy-to-use and promise-based Node.js ORM tool for Postgres, MySQL, MariaDB, SQLite, DB2, Microsoft SQL Server, and Snowflake. It features solid transaction support, relations, eager and lazy loading, read replication and more.

Would you like to contribute? Read our contribution guidelines to know more. There are many ways to help! 😃

🚀 Seeking New Maintainers for Sequelize! 🚀

We're looking for new maintainers to help finalize and release the next major version of Sequelize! If you're passionate about open-source and database ORMs, we'd love to have you onboard.

💰 Funding Available

We distribute $2,500 per quarter among maintainers and have additional funds for full-time contributions.

🛠️ What You’ll Work On

• Finalizing and releasing Sequelize’s next major version
• Improving TypeScript support and database integrations
• Fixing critical issues and shaping the ORM’s future

🤝 How to Get Involved

Interested? Join our Slack and reach out to @WikiRik or @sdepold:
➡️ sequelize.org/slack

We’d love to have you on board! 🚀

:computer: Getting Started

Ready to start using Sequelize? Head to sequelize.org to begin!

• Our Getting Started guide for Sequelize 6 (stable)

:money_with_wings: Supporting the project

Do you like Sequelize and would like to give back to the engineering team behind it?

We have recently created an OpenCollective based money pool which is shared amongst all core maintainers based on their contributions. Every support is wholeheartedly welcome. ❤️

:pencil: Major version changelog

Please find upgrade information to major versions here:

• Upgrade from v5 to v6

:book: Resources

• Documentation
• Databases Compatibility Table
• Changelog
• Discussions
• Slack
• Stack Overflow

:wrench: Tools

• CLI
• With TypeScript
• Enhanced TypeScript with decorators
• For GraphQL
• For CockroachDB
• Awesome Sequelize
• For YugabyteDB

:speech_balloon: Translations

• English (Official)
• 中文文档 (Unofficial)

:warning: Responsible disclosure

If you have security issues to report, please refer to our Responsible Disclosure Policy for more details.