How to build a public Gravity Forms integration: Building the Auth Flow

Hey there, fellow JavaScript enthusiast! Ready to dive into the world of Gravity Forms integration? Today, we're focusing on the crucial part of any integration: the authorization flow. Let's get your users connected securely and efficiently!

Introduction

Gravity Forms is a powerhouse for creating complex forms in WordPress, but its true potential shines when integrated with other systems. That's where you come in! By building a public integration, you're opening up a world of possibilities for users. The key to a smooth, secure integration? A rock-solid authorization flow.

Prerequisites

Before we jump in, make sure you've got:

• Node.js and npm installed
• A basic grasp of OAuth 2.0 (don't worry, we'll cover the specifics)
• Your favorite code editor ready to roll

Setting up the project

Let's kick things off:

mkdir gravity-forms-integration
cd gravity-forms-integration
npm init -y
npm install express axios dotenv

Great! Now you've got the basics set up.

Implementing the Authorization Flow

This is where the magic happens. We'll use the OAuth 2.0 authorization code flow with PKCE for extra security.

First, set up your OAuth client:

const axios = require('axios');
const crypto = require('crypto');

const clientId = process.env.CLIENT_ID;
const redirectUri = 'http://localhost:3000/callback';

function generateCodeVerifier() {
  return crypto.randomBytes(32).toString('hex');
}

function generateCodeChallenge(verifier) {
  return crypto.createHash('sha256').update(verifier).digest('base64')
    .replace(/\+/g, '-')
    .replace(/\//g, '_')
    .replace(/=/g, '');
}

Now, let's create the authorization request:

function getAuthorizationUrl() {
  const codeVerifier = generateCodeVerifier();
  const codeChallenge = generateCodeChallenge(codeVerifier);
  
  const params = new URLSearchParams({
    client_id: clientId,
    redirect_uri: redirectUri,
    response_type: 'code',
    code_challenge: codeChallenge,
    code_challenge_method: 'S256'
  });

  return `https://www.gravityforms.com/oauth/authorize?${params.toString()}`;
}

When the user completes the authorization, handle the callback and exchange the code for tokens:

async function handleCallback(code, codeVerifier) {
  const tokenResponse = await axios.post('https://www.gravityforms.com/oauth/token', {
    grant_type: 'authorization_code',
    code,
    client_id: clientId,
    redirect_uri: redirectUri,
    code_verifier: codeVerifier
  });

  return tokenResponse.data;
}

Building the User Interface

Keep it simple! A "Connect to Gravity Forms" button is all you need:

<button onclick="window.location.href='/connect'">Connect to Gravity Forms</button>

On your server:

app.get('/connect', (req, res) => {
  res.redirect(getAuthorizationUrl());
});

app.get('/callback', async (req, res) => {
  const { code } = req.query;
  const tokens = await handleCallback(code, req.session.codeVerifier);
  // Store tokens securely and redirect to success page
});

Securing the Integration

We've already implemented PKCE, which is awesome! For token revocation:

async function revokeToken(token) {
  await axios.post('https://www.gravityforms.com/oauth/revoke', {
    token,
    client_id: clientId
  });
}

Testing the Authorization Flow

Set up a simple Express server for testing:

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('<h1>Gravity Forms Integration</h1><a href="/connect">Connect</a>');
});

// Add your routes here

app.listen(3000, () => console.log('Server running on http://localhost:3000'));

Error Handling and Edge Cases

Always be prepared:

async function refreshToken(refreshToken) {
  try {
    const response = await axios.post('https://www.gravityforms.com/oauth/token', {
      grant_type: 'refresh_token',
      refresh_token: refreshToken,
      client_id: clientId
    });
    return response.data;
  } catch (error) {
    console.error('Error refreshing token:', error);
    // Handle the error (e.g., redirect to re-authorization)
  }
}

Best Practices

• Never store tokens in plain text. Use encryption or a secure key management system.
• Implement rate limiting to prevent abuse:

const rateLimit = require('express-rate-limit');

const apiLimiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100 // limit each IP to 100 requests per windowMs
});

app.use('/api/', apiLimiter);

Conclusion

And there you have it! You've just built a secure, efficient authorization flow for your Gravity Forms integration. Remember, this is just the beginning. From here, you can start adding features like form creation, submission handling, and data synchronization.

Keep exploring, keep coding, and most importantly, keep having fun with it! Your users are going to love what you build. Happy integrating!