Introduction
Integrating Sequelize ORM with NestJS leverages the power of type-safe database operations in scalable, server-side applications. This guide illustrates the setup and usage through step-wise code examples.
Setting Up a NestJS Project
Begin by establishing your base NestJS project. If you haven’t already done so, install NestJS CLI and create a new app:
npm i -g @nestjs/cli
nestjs new project-name
Navigate to your project directory:
cd project-name
Installing Sequelize and Dependencies
Install Sequelize, the Sequelize TypeScript typings, and the relevant database driver (e.g., PostgreSQL, MySQL):
npm install --save sequelize sequelize-typescript pg pg-hstore
npm install --save-dev @types/sequelize
Database Connection Configuration
Configure your database connection within the app module:
import { Module } from '@nestjs/common';
import { SequelizeModule } from '@nestjs/sequelize';
@Module({
imports: [
SequelizeModule.forRoot({
dialect: 'postgres',
host: 'localhost',
port: 5432,
username: 'user',
password: 'password',
database: 'db',
models: [], // Add your models here
}),
],
})
export class AppModule {}
Creating a Model
Define your first model with decorators to describe the table:
import { Table, Column, Model } from 'sequelize-typescript';
@Table
export class User extends Model {
@Column
firstName: string;
@Column
lastName: string;
// Add other fields and relationships
}
Add the model to your app module’s imports:
imports: [
SequelizeModule.forRoot({
//...
models: [User],
}),
]
Creating a Service
Develop services to handle business logic:
import { Injectable } from '@nestjs/common';
import { InjectModel } from '@nestjs/sequelize';
import { User } from './user.model';
@Injectable()
export class UserService {
constructor(
@InjectModel(User)
private userModel: typeof User,
) {}
async findAll(): Promise<User[]> {
return this.userModel.findAll();
}
// Define other service methods
}
Implementing Controllers
Use controllers to handle incoming requests and interact with services:
import { Controller, Get } from '@nestjs/common';
import { UserService } from './user.service';
import { User } from './user.model';
@Controller('users')
export class UserController {
constructor(private readonly userService: UserService) {}
@Get()
findAll(): Promise<User[]> {
return this.userService.findAll();
}
// Map more routes to actions
}
Advanced Topics: Associations and Transactions
Dive into advanced features by establishing model associations and managing transactions. Use decorators to define relations:
import { ForeignKey, BelongsTo } from 'sequelize-typescript';
import { Profile } from './profile.model';
@Table
export class User extends Model {
//...
@ForeignKey(() => Profile)
@Column
profileId: number;
@BelongsTo(() => Profile)
profile: Profile;
}
Manage complex operations with transactions:
import { Sequelize } from 'sequelize-typescript';
//...
async createUserWithProfile(userData, profileData) {
return this.sequelize.transaction(async (t) => {
const user = await this.userModel.create(userData, { transaction: t });
await user.createProfile(profileData, { transaction: t });
return user;
});
}
Handling Migrations
For database changes, Sequelize CLI and migrations keep your schema version-controlled:
npm install --save-dev sequelize-cli
npx sequelize-cli init
Generate and run new migrations:
npx sequelize-cli migration:generate --name add-users-table
npx sequelize-cli db:migrate
Conclusion
Sequelize with NestJS brings robustness to data handling in Node.js applications. By following this guide, you can now configure, use, and manage a type-safe database setup within your NestJS projects.
