Prisma ORM: Setting Up with an Express.js Project and PostgreSQL

Overview

In this article, we will go through the steps required to set up Prisma ORM in an Express.js project specifically for PostgreSQL. This setup will lay the foundation for interacting with your PostgreSQL database through Prisma in future articles.

Prerequisites

Before we proceed, make sure you have the following installed:

• Node.js (version 14 or later)

• PostgreSQL (a running instance)

• npm or yarn (as a package manager)

Step 1: Create a New Express.js Project

Open your terminal and create a new directory for your project:

mkdir prisma-express-postgres
cd prisma-express-postgres

Initialize a new Node.js project:

npm init -y

Step 2: Install Required Dependencies

Install Express.js and Prisma as dependencies:

npm install express
npm install prisma --save-dev

You also need to install the PostgreSQL client for Node.js:

npm install @prisma/client

Step 3: Initialize Prisma

Next, initialize Prisma in your project:

npx prisma init

This command creates a prisma directory containing a schema.prisma file, along with a .env file for environment variables.

Step 4: Configure PostgreSQL Connection

Open the .env file and set up your PostgreSQL connection string. Replace the placeholders with your actual database credentials:

ATABASE_URL="postgresql://USER:PASSWORD@localhost:5432/DATABASE_NAME?schema=public"

Make sure to use the correct USER, PASSWORD, and DATABASE_NAME.

Step 5: Define Your Database Schema

Open the schema.prisma file in the prisma directory and define your data model. For this example, let’s create a simple User model:

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

generator client {
  provider = "prisma-client-js"
}

model User {
  id    Int    @id @default(autoincrement())
  name  String
  email String @unique
}

Step 6: Run Migrations

After defining your data model, you need to create the database tables based on your schema. Run the following command to create a migration:

npx prisma migrate dev --name init

This command creates a new migration file and applies it to your database.

Step 7: Generate the Prisma Client

Now, generate the Prisma Client, which provides a type-safe query API:

npx prisma generate

Step 8: Create a Basic Express Server

Next, create a new file named server.js in your project root. Add the following code to set up a basic Express server:

const express = require('express');
const { PrismaClient } = require('@prisma/client');

const app = express();
const prisma = new PrismaClient();

app.use(express.json());

app.get('/', (req, res) => {
  res.send('Hello, Prisma with Express and PostgreSQL!');
});

const PORT = process.env.PORT || 3000;

app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});

Step 9: Start the Server

Finally, run the server with the following command:

node server.js

Visit http://localhost:3000 in your browser, and you should see the message "Hello, Prisma with Express and PostgreSQL!"

Conclusion

In this article, we walked through the setup of Prisma ORM in an Express.js project configured for PostgreSQL. We established a connection to the database, defined a data model, and created a basic Express server. In the next article, we will explore how to define models with the Prisma schema in more detail.