How to build a public PandaDoc integration: Building the Auth Flow

Hey there, fellow JavaScript enthusiast! Ready to dive into the world of PandaDoc integration? Today, we're going to focus on one of the most crucial aspects of building a public integration: the authorization flow. Don't worry, it's not as daunting as it sounds. Let's break it down step by step.

Introduction

PandaDoc's API is a powerful tool that allows you to create, manage, and track documents programmatically. But before we can start playing with documents, we need to make sure our app has the proper permissions. That's where the auth flow comes in.

Prerequisites

Before we start, make sure you've got:

• PandaDoc API credentials (if you don't have these yet, head over to the PandaDoc developer portal)
• A Node.js environment set up with Express.js

Got those? Great! Let's dive in.

OAuth 2.0 Flow Overview

We'll be using the Authorization Code Grant type of OAuth 2.0. It's a bit like a secret handshake between your app and PandaDoc. Here's the gist:

1. Your app asks for permission
2. The user grants it
3. PandaDoc gives you a special code
4. You exchange that code for access tokens

Simple, right? Let's build it out.

Setting up the Authorization Request

First things first, we need to construct the authorization URL. It'll look something like this:

const authUrl = `https://app.pandadoc.com/oauth2/authorize?client_id=${YOUR_CLIENT_ID}&redirect_uri=${YOUR_REDIRECT_URI}&scope=read+write&response_type=code`;

Now, set up an endpoint in your Express app to handle the redirect:

app.get('/callback', (req, res) => {
  // We'll fill this in soon!
});

Handling the Authorization Code

When the user grants permission, PandaDoc will redirect them back to your app with a code. Let's grab it:

app.get('/callback', (req, res) => {
  const code = req.query.code;
  if (code) {
    // Success! Let's exchange this for tokens
  } else {
    // Uh oh, something went wrong
  }
});

Token Exchange

Now for the fun part! Let's exchange that code for some shiny new tokens:

const axios = require('axios');

// ... in your callback route
const tokenResponse = await axios.post('https://api.pandadoc.com/oauth2/access_token', {
  grant_type: 'authorization_code',
  code: code,
  client_id: YOUR_CLIENT_ID,
  client_secret: YOUR_CLIENT_SECRET,
  redirect_uri: YOUR_REDIRECT_URI
});

const { access_token, refresh_token } = tokenResponse.data;
// Store these securely!

Implementing Token Refresh

Access tokens don't last forever. When they expire, use the refresh token to get a new one:

const refreshTokens = async (refresh_token) => {
  const response = await axios.post('https://api.pandadoc.com/oauth2/access_token', {
    grant_type: 'refresh_token',
    refresh_token: refresh_token,
    client_id: YOUR_CLIENT_ID,
    client_secret: YOUR_CLIENT_SECRET
  });
  return response.data;
};

Using the Access Token

Now you're ready to make authenticated requests to PandaDoc:

const makeApiRequest = async (accessToken) => {
  try {
    const response = await axios.get('https://api.pandadoc.com/public/v1/documents', {
      headers: { Authorization: `Bearer ${accessToken}` }
    });
    return response.data;
  } catch (error) {
    if (error.response && error.response.status === 401) {
      // Time to refresh that token!
    }
  }
};

Security Considerations

Remember:

• Always use HTTPS
• Implement the state parameter to prevent CSRF attacks
• Store tokens securely (not in local storage!)

Testing the Auth Flow

Give it a spin! Try logging in, creating a document, and refreshing your access token. If you're feeling ambitious, write some automated tests to ensure everything's working smoothly.

Conclusion

And there you have it! You've just built a robust auth flow for your PandaDoc integration. Pat yourself on the back – you've tackled one of the trickiest parts of API integration.

Next up, you might want to explore more of PandaDoc's API endpoints and start building out the core functionality of your integration. The world of document automation is your oyster!

Remember, the key to a great integration is a solid foundation, and that's exactly what you've built here. Keep coding, keep learning, and most importantly, have fun with it!