NestJS Enterprise Backend APIs · Lesson

TypeORM Integration Basics

Set up TypeORM with NestJS, define entities, and perform basic database operations using repositories.

TypeORM Integration Basics is a free NestJS Enterprise Backend APIs lesson on CoddyKit — lesson 3 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the NestJS Enterprise Backend APIs learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Intro to TypeORM in NestJS

Welcome to integrating TypeORM with NestJS! TypeORM is an Object-Relational Mapper (ORM) that helps you work with databases using TypeScript or JavaScript.

Instead of writing raw SQL queries, you interact with your database using familiar object-oriented programming concepts like classes and objects.

Why Use an ORM?

ORMs like TypeORM offer several benefits:

Abstraction: No need to write complex SQL.
Type Safety: With TypeScript, your database interactions are type-checked.
Portability: Easily switch between different database systems (PostgreSQL, MySQL, SQLite, etc.).
Productivity: Faster development with less boilerplate code.

Setting Up TypeORM Module

First, we need to install TypeORM and the database driver for your chosen database (e.g., pg for PostgreSQL, sqlite3 for SQLite).

Then, we configure the TypeOrmModule in your main application module (usually AppModule) to establish the database connection.

TypeOrmModule Configuration

Here's how you might configure TypeORM in your app.module.ts. This example uses SQLite for simplicity, which stores data in a file.

We use TypeOrmModule.forRoot() to set up the connection globally.

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

@Module({
  imports: [
    TypeOrmModule.forRoot({
      type: 'sqlite',
      database: 'db.sqlite',
      entities: [], // We'll add our entities here soon!
      synchronize: true, // Auto-create tables (dev only!)
    }),
  ],
  controllers: [],
  providers: [],
})
export class AppModule {}

Defining Your First Entity

An Entity is a class that maps directly to a database table. Each instance of the entity class represents a row in that table.

We use decorators like @Entity(), @PrimaryGeneratedColumn(), and @Column() to define the table and its columns.

User Entity Example

Let's create a simple User entity. This will map to a user table in our database.

@PrimaryGeneratedColumn() creates an auto-incrementing primary key.
@Column() defines a regular column.

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

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

  @Column()
  firstName: string;

  @Column()
  lastName: string;

  @Column({ default: true })
  isActive: boolean;
}

Registering Entities in Module

After defining your entity, you need to tell TypeORM about it. Update your AppModule's TypeOrmModule.forRoot() configuration to include your new User entity.

This allows TypeORM to create the corresponding table in your database.

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { User } from './user.entity'; // Import your entity

@Module({
  imports: [
    TypeOrmModule.forRoot({
      type: 'sqlite',
      database: 'db.sqlite',
      entities: [User], // Register your User entity here
      synchronize: true,
    }),
  ],
  controllers: [],
  providers: [],
})
export class AppModule {}

Introducing Repositories

TypeORM Repositories are objects that provide methods for interacting with a specific entity's table in the database.

You inject a repository into your NestJS service (e.g., UserService) to perform CRUD operations (Create, Read, Update, Delete).

Basic Operations: Create & Read

To use a repository, you inject it using @InjectRepository(). Let's see how to create a new user and retrieve all users.

save(): Inserts a new record or updates an existing one.
find(): Retrieves all records for the entity.

import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { User } from './user.entity';

@Injectable()
export class UserService {
  constructor(
    @InjectRepository(User)
    private usersRepository: Repository<User>,
  ) {}

  async createUser(): Promise<User> {
    const newUser = this.usersRepository.create({
      firstName: 'Coddy',
      lastName: 'Kit',
      isActive: true,
    });
    return this.usersRepository.save(newUser);
  }

  async findAll(): Promise<User[]> {
    return this.usersRepository.find();
  }
}

TypeORM Quick Check

Which decorator is used to mark a class as an entity that maps to a database table in TypeORM?

Recap: TypeORM Basics

You've learned the basics of integrating TypeORM into your NestJS application!

We configured TypeOrmModule in our AppModule.
We defined an Entity using decorators like @Entity(), @PrimaryGeneratedColumn(), and @Column().
We understood how to use Repositories to perform basic database operations like creating and reading records.

Next, you'll explore more advanced CRUD operations and data handling techniques!

Frequently asked questions

Is the “TypeORM Integration Basics” lesson free?

Yes — the full text of “TypeORM Integration Basics” is free to read here on the web, and the NestJS Enterprise Backend APIs course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the NestJS Enterprise Backend APIs course, upgrade to CoddyKit PRO.

What will I learn in “TypeORM Integration Basics”?

Set up TypeORM with NestJS, define entities, and perform basic database operations using repositories. You practise NestJS Enterprise Backend APIs with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start NestJS Enterprise Backend APIs?

No prior experience is required. NestJS Enterprise Backend APIs on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 3, so you can start here or from the beginning and move at your own pace.

How long does the “TypeORM Integration Basics” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this NestJS Enterprise Backend APIs lesson?

Yes. Every NestJS Enterprise Backend APIs lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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