How to Build a Referral Program with Node.js

A referral program is a great way to acquire new users and retain existing ones by encouraging them to share your service. In this article, we will walk through building a simple referral system using Node.js, Express, and MongoDB.

Prerequisites

Before we begin, ensure you have the following installed:

• Node.js

• MongoDB

• Postman (optional for API testing)

Project Setup

First, create a new Node.js project and install the necessary dependencies:

mkdir referral-program
cd referral-program
npm init -y
npm install express mongoose uuid jsonwebtoken dotenv

• express: Web framework for Node.js.

• mongoose: MongoDB object modeling tool.

• uuid: Generates unique referral codes.

• jsonwebtoken: Handles authentication.

• dotenv: Loads environment variables.

Create a .env file for storing environment variables:

PORT=5000
MONGO_URI=your_mongodb_connection_string
JWT_SECRET=your_jwt_secret

Setting Up the Server

Create an index.js file and set up an Express server:

require('dotenv').config();
const express = require('express');
const mongoose = require('mongoose');

const app = express();
app.use(express.json());

mongoose.connect(process.env.MONGO_URI, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
}).then(() => console.log('MongoDB Connected'))
  .catch(err => console.log(err));

app.listen(process.env.PORT, () => {
    console.log(`Server running on port ${process.env.PORT}`);
});

Creating the Referral Model

Create a models/User.js file to define the user schema:

const mongoose = require('mongoose');
const { v4: uuidv4 } = require('uuid');

const UserSchema = new mongoose.Schema({
    name: String,
    email: { type: String, unique: true },
    referralCode: { type: String, default: uuidv4 },
    referredBy: { type: String, default: null },
    rewards: { type: Number, default: 0 },
});

module.exports = mongoose.model('User', UserSchema);

Creating Routes

Register a User with a Referral Code

Create a routes/user.js file:

const express = require('express');
const User = require('../models/User');
const router = express.Router();

router.post('/register', async (req, res) => {
    const { name, email, referralCode } = req.body;
    try {
        const referredBy = referralCode ? await User.findOne({ referralCode }) : null;
        const newUser = new User({
            name,
            email,
            referredBy: referredBy ? referredBy.referralCode : null
        });
        await newUser.save();

        if (referredBy) {
            referredBy.rewards += 10; // Reward the referrer
            await referredBy.save();
        }

        res.status(201).json({ message: 'User registered successfully', user: newUser });
    } catch (err) {
        res.status(500).json({ error: err.message });
    }
});

module.exports = router;

Integrating the Routes

Update index.js to use the user routes:

const userRoutes = require('./routes/user');
app.use('/api/users', userRoutes);

Testing the API

Use Postman or cURL to test the API:

1. Register a user without a referral code:

    POST http://localhost:5000/api/users/register
    {
       "name": "John Doe",
       "email": "john@example.com"
    }
   

2. Register a user with a referral code:

    POST http://localhost:5000/api/users/register
    {
       "name": "Jane Doe",
       "email": "jane@example.com",
       "referralCode": "referral_code_of_existing_user"
    }
   

Conclusion

Congratulations! You have successfully built a simple referral program with Node.js and MongoDB. This can be expanded by integrating authentication, better reward logic, and frontend integration.