Building a Scalable REST API with NestJS and Prisma: A Step-by-Step Guide

Building a Scalable REST API with NestJS and Prisma

In this tutorial, we’ll explore how to create a scalable REST API using NestJS and Prisma. We’ll start by introducing the basics of NestJS and Prisma, then dive into creating a new project, setting up Prisma, and defining a database schema.

What is Prisma?

Prisma is a next-generation Node and TypeScript object-relational mapper (ORM) that provides a powerful database toolkit for building scalable and maintainable applications. With Prisma, you can define your data models and relations in a declarative way, making it easier to work with your database.

Why Use Prisma?

Prisma improves type safety by simplifying database access and reducing repetitive CRUD boilerplate. It’s easy to integrate with your preferred framework and is an ideal database toolkit for creating dependable and scalable web APIs.

Creating a New NestJS Project

To get started, make sure you have Node.js (≥v10.13.0, except for v13) installed, as well as Postman. Then, install the Nest CLI using the following command:

npm install -g @nestjs/cli

Once installed, create a new Nest project using the following command:

nest new my-nest-project

Choose npm as the preferred package manager and hit Enter.

Setting up Prisma

Install the Prisma CLI as a development dependency using the following command:

npm install --save-dev prisma

Then, invoke the Prisma CLI locally using npx:

npx prisma

Create your initial Prisma setup using the Prisma init command:

npx prisma init

This will create a new Prisma directory with the following files:

• schema.prisma: specifies your database connection and contains the database schema
• .env: a dotenv file typically used to store your database credentials in a group of environment variables

Connecting to a Database

For this tutorial, we’ll connect to an SQLite database. Open the datasource/schema.prisma file and update the content with the following code:

datasource db {
provider = "sqlite"
url = env("DATABASE_URL")
}

Then, modify the .env file to specify the location of the database file:

DATABASE_URL="file:./dev.db"

Defining a Database Schema

Define a Todo schema in the schema.prisma file:

model Todo {
id Int @id @default(autoincrement())
title String
completed Boolean @default(false)
}

Generate your SQL migration files and run them against the database using the following command:

npx prisma migrate dev

Setting up Prisma Client

Install Prisma Client using the following command:

npm install @prisma/client

Create a prisma.service file in the src folder to abstract away the Prisma Client API for database queries:
“`
import { PrismaClient } from ‘@prisma/client’;

@Injectable()
export class PrismaService {
private readonly prisma: PrismaClient;

constructor() {
this.prisma = new PrismaClient();
}

async findAllTodos(): Promise

async createTodo(todo: Todo): Promise {
return this.prisma.todo.create({
data: todo,
});
}

async updateTodo(id: number, todo: Todo): Promise {
return this.prisma.todo.update({
where: { id },
data: todo,
});
}

async deleteTodo(id: number): Promise {
await this.prisma.todo.delete({
where: { id },
});
}
}
“`
Generating a Todo Module

Generate a Todo module using the following command:

nest generate module todo

Then, generate a service file for the Todo module:

nest generate service todo

Update the todo.service file with the following code:
“`
import { Injectable } from ‘@nestjs/common’;
import { PrismaService } from ‘./prisma.service’;

@Injectable()
export class TodoService {
constructor(private readonly prisma: PrismaService) {}

async findAllTodos(): Promise

async createTodo(todo: Todo): Promise {
return this.prisma.createTodo(todo);
}

async updateTodo(id: number, todo: Todo): Promise {
return this.prisma.updateTodo(id, todo);
}

async deleteTodo(id: number): Promise {
await this.prisma.deleteTodo(id);
}
}
“`
Testing the Application

Test the application using Postman. Send a GET request to http://localhost:3000/todos to retrieve all todos. Send a POST request to http://localhost:3000/todos to create a new todo. Send a PUT request to http://localhost:3000/todos/:id to update a todo. Send a DELETE request to http://localhost:3000/todos/:id to delete a todo.

That’s it! You’ve now built a scalable REST API using NestJS and Prisma.