Sequelize is a promise-based Node.js ORM tool that supports various databases such as Postgres, MySQL, MariaDB, SQLite, Microsoft SQL Server, Amazon Redshift, and Snowflake’s Data Cloud. It makes it easy for developers to interact with their databases in a simplified, more readable way. Essential features it offers include firm transaction support, relations, eager and lazy loading, read replication, and much more. Sequelize's goal is to provide a robust and easy-to-use tool easing data manipulation in Node.js applications.
To use Sequelize in your Node.js project, you need to install it first using npm. You can do this by running the command npm install --save sequelize. Once installed, you can require it in your file with const Sequelize = require('sequelize');. To establish a connection with the database, you can use the following code snippet:
const sequelize = new Sequelize('database', 'username', 'password', {
host: 'localhost',
dialect: /* one of 'mysql' | 'mariadb' | 'postgres' | 'mssql' */
});
To check whether the connection has been established use:
try {
await sequelize.authenticate();
console.log('Connection has been established successfully.');
} catch (error) {
console.error('Unable to connect to the database:', error);
}
To define a model you can use sequelize.define('modelName', attributes, options). For instance:
const User = sequelize.define('User', {
// Model attributes are defined here
firstName: {
type: DataTypes.STRING,
allowNull: false
},
lastName: {
type: DataTypes.STRING
// allowNull defaults to true
}
}, {
// Other model options go here
});
After defining models, you can perform various ORM operations such as create, find, update, etc.
The Sequelize official documentation is a comprehensive source for any Sequelize details you might require. You can find everything from getting started guides and code examples to version upgrade information and advanced topic discussions. The official Sequelize documentation can be accessed at: https://sequelize.org.
