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Version: v7 - alpha

Getting Started

In this tutorial you will learn to make a simple setup of Sequelize.

Installing​

Sequelize is available via npm (or yarn).

info

The following commands will install Sequelize v7. If you're looking for Sequelize v6 (published as sequelize instead of @sequelize/core), visit the v6 documentation

# This will install Sequelize 7, the latest alpha release of Sequelize
npm i @sequelize/core@alpha

Connecting to a database​

To connect to the database, you must create a Sequelize instance, and pass it the database configuration information, such as the dialect, the host, and the username and password.

Each dialect supports a different set of options. Follow the links below to see how to connect to your database:

If your database is not listed above, Sequelize does not support it out of the box. However, Sequelize is extensible, and you can create your own dialect, or find a community-maintained one. For more information, see our documentation about supporting other databases.

Here is a short example of how to connect to a SQLite database:

import { Sequelize } from '@sequelize/core';
import { SqliteDialect } from '@sequelize/sqlite3';

const sequelize = new Sequelize({
  dialect: SqliteDialect,
});

The Sequelize constructor accepts many options. They are documented in the API Reference.

Testing the connection​

You can use the .authenticate() function to test if the connection is OK. Note that this is completely optional, but recommended as Sequelize fetches your Database version on the first connection. That version is then used to determine which SQL features are available.

try {
  await sequelize.authenticate();
  console.log('Connection has been established successfully.');
} catch (error) {
  console.error('Unable to connect to the database:', error);
}

Closing the connection​

Sequelize uses a connection pool to manage connections to the database. This means some connection can remain open even after you're done with them. If you wish to gracefully shut down your application, you can use sequelize.close() to close all active connections.

caution

Once sequelize.close() has been called, it's impossible to open a new connection. You will need to create a new Sequelize instance to access your database again.

Terminology convention​

Observe that, in the examples above, Sequelize refers to the library itself while the lowercase sequelize refers to an instance of Sequelize. This is the recommended convention, and it will be followed throughout the documentation.

TypeScript​

Sequelize provides built-in TypeScript support.

Head to the Version Policy page to know which versions of TypeScript are supported, and make sure that the @types/node package corresponding to your Node.js version is installed in your project.

info

Sequelize makes use of the the exports package.json field. You may need to update your tsconfig.json configuration to make sure TypeScript's module resolution supports it.

At time of writing (TS 5.4), this can be done in two ways:

CommonJS or ESM?​

Our documentation makes heavy use of ECMAScript Modules (ESM), but CommonJS is fully supported by Sequelize. To use Sequelize in a CommonJS project, simply use require instead of import:

// how you would import Sequelize in ESM
import { Sequelize, Op, Model, DataTypes } from '@sequelize/core';

// how you would import Sequelize in CommonJS
const { Sequelize, Op, Model, DataTypes } = require('@sequelize/core');

Most of the methods provided by Sequelize are asynchronous and therefore return Promises. we highly recommend using ECMAScript Modules, as they give you access to Top-Level Await, which we use extensively in our examples. Head to Node.js' documentation to learn how to use them in Node.js.

Logging​

To ease debugging, you can enable logging in Sequelize. This is done by setting the logging option to a function that gets executed every time Sequelize needs to log something.

Examples:

const sequelize = new Sequelize({
  dialect: SqliteDialect,

  // Disables logging (default)
  logging: false,

  // Sends the logging output to the console
  logging: console.log,

  // You can also use an arbitrary function, which can be used to send logs to a logging tool
  logging: (...msg) => console.log(msg),
});
tip

If you need to log only specific queries, you can use the logging option in all model methods that execute queries, as well as all queryInterface methods.

Next Step​

Now that you have a Sequelize instance, the next step to get started is to define your first models.