TypeORM in NestJS

Nest doesn’t ship a database layer — you choose one. TypeORM is the most common pick, partly because it was written in TypeScript from day one and partly because @nestjs/typeorm makes setup feel native.

Install

npm i @nestjs/typeorm typeorm pg

You’ll need the driver for your database. pg for Postgres, mysql2 for MySQL/MariaDB, sqlite3 for SQLite, and so on.

Wire It Up

Register the connection once in AppModule. Every feature module will share it.

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';

@Module({
  imports: [
    TypeOrmModule.forRoot({
      type: 'postgres',
      host: 'localhost',
      port: 5432,
      username: 'postgres',
      password: 'secret',
      database: 'app',
      entities: [__dirname + '/**/*.entity{.ts,.js}'],
      synchronize: false,
    }),
  ],
})
export class AppModule {}

synchronize: true auto-creates tables from your entities. It’s wonderful for prototyping and dangerous in production — one rename and your data is gone. Use migrations for any real environment.

The Workflow at a Glance

The pieces you’ll meet over the next few lessons:

1. Entity — a class decorated with @Entity() that maps to a table.
2. Repository — Nest auto-creates one per entity. It has methods like find, findOne, save, delete.
3. Service — injects the repository and exposes business operations.

@Injectable()
export class UsersService {
  constructor(
    @InjectRepository(User) private readonly repo: Repository<User>,
  ) {}

  findAll() {
    return this.repo.find();
  }
}

That Repository<User> is the heart of it — a generic class you’ll be seeing a lot.