Development & Testing

TypeORM

Feature-rich ORM for TypeScript and JavaScript supporting Active Record and Data Mapper patterns with decorators.

Claude Code Codex Copilot Cursor Windsurf

Overview

TypeORM is a mature ORM that supports both Active Record and Data Mapper patterns, making it versatile for different architectural preferences. It uses TypeScript decorators to define entities, making the schema definition expressive and colocated with your model classes. AI agents can generate entity definitions, write repository queries, and manage migrations with full type awareness.

The framework supports PostgreSQL, MySQL, MariaDB, SQLite, MS SQL Server, Oracle, and MongoDB. It provides a powerful QueryBuilder for complex queries, supports eager and lazy relations, and includes a migration system that can auto-generate migrations from entity changes. Your AI agent can navigate these features to build robust data access layers.

TypeORM is widely used in NestJS applications where its decorator-based approach aligns with NestJS's own patterns. Your AI agent can set up the TypeORM module, define entities with validations, create custom repositories, and implement database transactions for complex business logic.

Who Is This For?

NestJS developers building enterprise-grade backend services
Teams preferring decorator-based entity definitions for database models
Developers needing Active Record pattern for rapid prototyping
Projects requiring support for multiple database engines simultaneously

Installation

Setup for Claude Code

npm install typeorm reflect-metadata pg
npm install -D @types/node
Claude Code generates entities and migrations via bash

Configuration

// data-source.ts
import { DataSource } from "typeorm";
export const AppDataSource = new DataSource({
  type: "postgres",
  host: "localhost",
  port: 5432,
  username: "dev",
  password: "dev",
  database: "myapp",
  entities: ["src/entities/*.ts"],
  migrations: ["src/migrations/*.ts"],
  synchronize: false,
});