Connect Node.js to NeonDB(PSQL)

If you're building a Node.js application and looking to connect it to a modern, serverless PostgreSQL database like Neon, this guide walks you through a simple, functional setup using the pg library.

In this example, we build a basic Student Management API using Express.js and PostgreSQL hosted on NeonDB.

Prerequisites

Before jumping in, ensure you have:

• Node.js and npm installed (I have used node v20)

• A NeonDB project and database created

• Your Neon connection string (from the Neon dashboard)

• A .env file in your project with:

DATABASE_URL=your_neon_connection_string

Setting Up the Database Connection

We use the pg library to connect to Neon. The configuration is simple and uses a connection string from the .env file:

api-handler.js

const pg = require("pg");
const { Pool } = pg;
const dotenv = require("dotenv");
dotenv.config();

const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
});

This initializes a pool of connections to NeonDB. This setup is scalable and production-friendly.

API Endpoints Overview

Here's what the API supports:

All these handlers are defined in api-handler.js, making use of async/await and parameterized queries to avoid SQL injection.

Example: Add a Student

To add a student, the handler dynamically builds the insert query based on the request body:

exports.addStudentEntry = (req, res) => {
  const { name, age, department } = req.body;
  const dbArgs = Object.keys(req.body);
  const dbVals = [name, age, department];

  const query = `INSERT INTO students(${dbArgs.join(",")}) VALUES($1,$2,$3) RETURNING *;`;

  pool.query(query, dbVals)
    .then((result) => res.send(result.rows[0]))
    .catch((e) => console.log("Insert error:", e));
};

This is clean, safe, and works perfectly with PostgreSQL on Neon.

Starting the Express Server

The Express app is simple and loads routes directly from api-handler.js.

index.js

const express = require("express");
const cors = require("cors");
const dotenv = require("dotenv");
dotenv.config();

const {
  getHealthCheck,
  getStudentById,
  getAllStudents,
  addStudentEntry,
  updateStudentEntry,
  deleteStudentEntry,
} = require("./api-handler");

const app = express();
const port = 3000;

app.use(cors({ origin: "*" })); // this is for illustration purpose DO NOT THIS ON PRODUCTION
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

app.get("/v1/healthcheck", getHealthCheck);
app.get("/v1/students/:id", getStudentById);
app.route("/v1/students")
  .get(getAllStudents)
  .post(addStudentEntry);
app.route("/v1/students/:id")
  .put(updateStudentEntry)
  .delete(deleteStudentEntry);

app.listen(port, () => {
  console.log(`Server running at http://127.0.0.1:${port}`);
});

Testing Your Setup

1. Ensure your .env has the correct NeonDB connection string.

2. Run the app:

node index.js

3. Use curl, Postman, or a browser to test endpoints like:

curl http://localhost:3001/v1/students