Sequelize vs. TypeORM: Choosing the Right ORM for Your Node.js Project

6 min readAug 13, 2023

Introduction:

In the world of Node.js development, choosing the right Object-Relational Mapping (ORM) tool can greatly impact your project’s efficiency and maintainability. Two popular choices, Sequelize and TypeORM, offer developers powerful solutions for database interactions. In this quick 5-minute read, we’ll explore the strengths and nuances of both ORMs through examples to help you make an informed decision.

Sequelize: The Established Player 🏁

Sequelize has been a stalwart in the Node.js ecosystem for years. It supports multiple relational databases and provides a comprehensive set of features for model definition, associations, and database operations.

Advantages of Sequelize:

Flexibility: Sequelize’s wide compatibility makes it a great choice for projects using different databases.
Mature Ecosystem: Extensive documentation and a large community mean you’ll find ample resources for troubleshooting.
Raw SQL Queries: For cases requiring raw SQL, Sequelize allows you to execute queries directly.

Example: Defining Models and Associations in Sequelize

// Sequelize model definition
const User = sequelize.define('User', {
  username: Sequelize.STRING,
  email: Sequelize.STRING
});

// Defining associations
User.hasMany(Post);
Post.belongsTo(User);

TypeORM: The Rising Star ⭐

TypeORM is a newer player but has gained significant traction for its TypeScript-first approach. It seamlessly combines the worlds of Object-Relational Mapping and TypeScript’s type safety.

Advantages of TypeORM:

TypeScript Integration: TypeORM natively embraces TypeScript, providing strong typing and compile-time checks.
Decorators: Using decorators, you can define entities and relationships right in your TypeScript classes.
Automated Migrations: TypeORM simplifies database schema changes by offering automatic migrations.

Example: Defining Models and Associations in TypeORM

// TypeORM entity definition
@Entity()
class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  username: string;

  @Column()
  email: string;

  @OneToMany(() => Post, post => post.user)
  posts: Post[];
}

Comparing the Features 📊

Model Definition:

Sequelize: Models are defined using JavaScript classes and configurations.

const { Sequelize, DataTypes } = require('sequelize');
const sequelize = new Sequelize('database', 'username', 'password', {
  host: 'localhost',
  dialect: 'mysql'
});

const User = sequelize.define('User', {
  username: {
    type: DataTypes.STRING,
    allowNull: false
  },
  email: {
    type: DataTypes.STRING,
    allowNull: false
  }
});

const Post = sequelize.define('Post', {
  title: {
    type: DataTypes.STRING,
    allowNull: false
  },
  content: {
    type: DataTypes.TEXT,
    allowNull: true
  }
});

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

// Sync models to the database
sequelize.sync();

TypeORM: Models can be defined using TypeScript classes with decorators for properties and relationships.

import { Entity, PrimaryGeneratedColumn, Column, OneToMany, ManyToOne } from 'typeorm';

@Entity()
export class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  username: string;

  @Column()
  email: string;

  @OneToMany(() => Post, post => post.user)
  posts: Post[];
}

@Entity()
export class Post {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  title: string;

  @Column()
  content: string;

  @ManyToOne(() => User, user => user.posts)
  user: User;
}

In Sequelize, models are defined using the sequelize.define method with JavaScript classes and configurations for each field. In TypeORM, models are defined using TypeScript classes with decorators (@Entity, @Column, @OneToMany, @ManyToOne) to specify properties, relationships, and entity mapping.

Associations:

Sequelize: Offers a wide range of associations, including one-to-one, one-to-many, and many-to-many.

// Sequelize model definition
const { Sequelize, DataTypes } = require('sequelize');
const sequelize = new Sequelize('database', 'username', 'password', {
  host: 'localhost',
  dialect: 'mysql'
});

const User = sequelize.define('User', {
  username: DataTypes.STRING,
  email: DataTypes.STRING
});

const Post = sequelize.define('Post', {
  title: DataTypes.STRING,
  content: DataTypes.TEXT
});

// Define associations
User.hasMany(Post);    // One-to-Many
Post.belongsTo(User);  // Many-to-One

// Sync models to the database
sequelize.sync();

TypeORM: Provides similar association types with decorators for relationships.

import { Entity, PrimaryGeneratedColumn, Column, OneToMany, ManyToOne } from 'typeorm';

@Entity()
export class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  username: string;

  @Column()
  email: string;

  @OneToMany(() => Post, post => post.user)  // One-to-Many
  posts: Post[];
}

@Entity()
export class Post {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  title: string;

  @Column()
  content: string;

  @ManyToOne(() => User, user => user.posts)  // Many-to-One
  user: User;
}

In both Sequelize and TypeORM, associations are established using decorators (@OneToMany and @ManyToOne in TypeORM, similar methods in Sequelize) to specify the type of relationship between entities. These associations define how entities are related, whether it's a one-to-one, one-to-many, or many-to-one relationship.

Querying:

Sequelize: Employs a functional query language for complex queries and supports raw SQL queries.

const { Sequelize, DataTypes } = require('sequelize');
const sequelize = new Sequelize('database', 'username', 'password', {
  host: 'localhost',
  dialect: 'mysql'
});

const User = sequelize.define('User', {
  username: DataTypes.STRING,
  email: DataTypes.STRING
});

// Querying with functional language
User.findOne({
  where: { username: 'john' }
}).then(user => {
  console.log(user);
});

// Raw SQL query
sequelize.query("SELECT * FROM Users WHERE username = 'john'", { type: sequelize.QueryTypes.SELECT })
  .then(users => {
    console.log(users);
  });

TypeORM: Offers a query builder for complex queries and raw SQL query execution.

import { Entity, PrimaryGeneratedColumn, Column, getConnection } from 'typeorm';

@Entity()
export class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  username: string;

  @Column()
  email: string;
}

// Querying with query builder
const user = await getConnection()
  .getRepository(User)
  .createQueryBuilder('user')
  .where('user.username = :username', { username: 'john' })
  .getOne();

console.log(user);

// Raw SQL query
const users = await getConnection().query("SELECT * FROM user WHERE username = 'john'");
console.log(users);

Both Sequelize and TypeORM provide means to perform complex queries and execute raw SQL queries when needed. Sequelize uses a functional query language for complex queries and provides support for raw SQL queries. TypeORM offers a query builder to construct complex queries in a fluent and TypeScript-friendly way, along with the ability to execute raw SQL queries for more advanced scenarios.

Migrations:

Sequelize: Requires manual migrations defined in scripts.

Migrations in Sequelize involve creating separate migration files to define changes in the database schema. These files are manually created and executed to apply changes to the database.

Example: Creating a Migration in Sequelize

# Generate a migration file
npx sequelize-cli migration:generate --name add-new-field-to-user

# Edit the generated migration file to define changes
# For example, adding a new field 'age' to the User table

# Run the migration to apply changes
npx sequelize-cli db:migrate

TypeORM: Supports automatic migrations based on changes in entity definitions.

TypeORM simplifies migrations by allowing automatic generation and execution of migrations based on changes in entity definitions.

Example: Automatic Migrations in TypeORM

// Update the entity definition to include a new field 'age'
@Entity()
export class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  username: string;

  @Column()
  email: string;

  @Column()
  age: number; // New field
}

TypeORM can automatically generate a migration for the changes made in the entity definition:

# Generate and run migrations
npx typeorm migration:generate -n AddAgeColumn
npx typeorm migration:run

With TypeORM, the migration files are automatically generated based on changes to entity definitions, streamlining the process of adapting your database schema.

Migrations are crucial when your database schema evolves over time. Sequelize requires manual generation and execution of migration scripts, while TypeORM simplifies this process by offering automatic migration generation and execution based on changes in entity definitions.

Community and Adoption:

Sequelize: Established with a large and active community.
TypeORM: Growing rapidly, gaining popularity, especially among TypeScript enthusiasts.

Sequelize GitHub Repository: https://github.com/sequelize/sequelize

TypeORM GitHub Repository: https://github.com/typeorm/typeorm

Conclusion: The Perfect Fit for Your Project 🛠️

Choosing between Sequelize and TypeORM depends on your project’s requirements and your familiarity with TypeScript. Sequelize brings flexibility and maturity, making it suitable for a wide range of projects. On the other hand, TypeORM’s TypeScript-first approach offers type safety and seamless integration for TypeScript-heavy applications.

Consider your project’s complexity, your team’s expertise, and your preference for TypeScript when making your decision. Whether you opt for the tried-and-true Sequelize or the TypeScript-powered TypeORM, both ORMs offer powerful tools to simplify your database interactions and enhance your Node.js application.