Getting started

This guide takes a NestJS app from nothing to a GraphQL API over a PostgreSQL database. The same steps work for any supported database: only the driver and the URL change.

Requirements

• Node.js 24 or later
• NestJS 12 with @nestjs/graphql 14 and Apollo Server 5
• A database you can connect to

1. Install

Install the library, its peer dependencies, and the driver of your database:

npm install @nestjs-modules/inverse-model \
  @nestjs/graphql @nestjs/apollo @apollo/server @as-integrations/express5 graphql \
  typeorm pg

Database	Driver package
PostgreSQL	pg
MySQL, MariaDB	mysql2
SQL Server	mssql
MongoDB	mongodb

TypeORM reads the SQL databases. It is a peer dependency of the module, so install it with MongoDB too.

2. Import the module

// app.module.ts
import { Module } from '@nestjs/common';
import { InverseModelModule } from '@nestjs-modules/inverse-model';

@Module({
  imports: [InverseModelModule.forRoot({ url: process.env.DATABASE_URL! })],
})
export class AppModule {}

// main.ts
import 'reflect-metadata';
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  await app.listen(3000);
}

bootstrap();

3. Start it

DATABASE_URL=postgres://user:pass@localhost:5432/blog node dist/main.js

On start the log says how many tables it read. The API is served at http://localhost:3000/graphql.

4. Query it

For a database with authors and blog_posts, where blog_posts.author_id references authors.id:

{
  blogPosts(where: { title: { contains: "graphql" } }, orderBy: [{ id: DESC }], limit: 5) {
    title
    author { fullName }
  }
  authorsCount
}

mutation {
  createAuthor(input: { fullName: "Ada Lovelace", email: "ada@example.com" }) {
    id
    createdAt
  }
}

Try it with the sample database

The repository ships a blog schema for every database and a Docker Compose file that loads it:

git clone https://github.com/nest-modules/inverse-model.git
cd inverse-model
docker compose up -d --wait postgres
DATABASE_URL=postgres://inverse:inverse@postgres:5432/inverse_blog docker compose up -d --build --wait app

The API is then at http://localhost:3000/graphql.

Or start from the CLI

The CLI writes a ready-to-run project around the module:

npm install -g @nestjs-modules/inverse
inverse generate postgres://user:pass@localhost:5432/blog -o blog-api

See CLI.

Next steps

• The generated API: every query and mutation you get.
• Security: narrow the API down before it reaches production.
• Options: everything forRoot accepts.