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

Hey there, fellow JavaScript enthusiasts! Ready to dive into the world of DocSend integration? Let's focus on the most crucial part: building a rock-solid auth flow. Buckle up, because we're about to make your integration dreams come true!

The Why and What

DocSend is a powerhouse for secure document sharing, and integrating it into your app can be a game-changer. But here's the thing: without a proper auth flow, you're basically trying to drive a car without keys. Not gonna happen, right? So let's nail this auth flow and set ourselves up for success.

Before We Jump In

Make sure you've got these in your toolbelt:

• DocSend API credentials (if you don't have 'em, go grab 'em!)
• A Node.js and Express.js setup (I know you've got this)
• A good grasp on OAuth 2.0 (it's our best friend in this journey)

Setting the Stage

First things first, let's get our project ready:

mkdir docsend-integration && cd docsend-integration
npm init -y
npm install express axios dotenv

Create an .env file for your secrets:

DOCSEND_CLIENT_ID=your_client_id
DOCSEND_CLIENT_SECRET=your_client_secret
REDIRECT_URI=http://localhost:3000/callback

The OAuth 2.0 Dance

Now, let's make some magic happen with OAuth 2.0:

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

const app = express();

const authorizationUrl = `https://docsend.com/oauth/authorize?client_id=${process.env.DOCSEND_CLIENT_ID}&redirect_uri=${process.env.REDIRECT_URI}&response_type=code`;

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

app.get('/callback', async (req, res) => {
  const { code } = req.query;
  
  try {
    const response = await axios.post('https://docsend.com/oauth/token', {
      client_id: process.env.DOCSEND_CLIENT_ID,
      client_secret: process.env.DOCSEND_CLIENT_SECRET,
      code,
      grant_type: 'authorization_code',
      redirect_uri: process.env.REDIRECT_URI
    });

    const { access_token, refresh_token } = response.data;
    // Store these tokens securely!
    
    res.send('Authorization successful!');
  } catch (error) {
    console.error('Error during token exchange:', error);
    res.status(500).send('Authorization failed');
  }
});

app.listen(3000, () => console.log('Server running on port 3000'));

Keeping Those Tokens Fresh

Remember, access tokens don't last forever. Let's implement a refresh mechanism:

async function refreshToken(refresh_token) {
  try {
    const response = await axios.post('https://docsend.com/oauth/token', {
      client_id: process.env.DOCSEND_CLIENT_ID,
      client_secret: process.env.DOCSEND_CLIENT_SECRET,
      refresh_token,
      grant_type: 'refresh_token'
    });

    return response.data.access_token;
  } catch (error) {
    console.error('Error refreshing token:', error);
    throw error;
  }
}

Linking DocSend to Your Users

You'll want to associate DocSend accounts with your app's users. Here's a simple way:

function linkDocSendAccount(userId, accessToken, refreshToken) {
  // Store in your database
  db.users.update(userId, { docSendAccessToken: accessToken, docSendRefreshToken: refreshToken });
}

When Things Go Sideways

Always be prepared for the unexpected:

app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send('Something broke! But we\'re on it.');
});

Taking It for a Spin

Test your auth flow manually by hitting your /auth endpoint and following the OAuth dance. For the overachievers, why not add some automated tests?

const request = require('supertest');

describe('Auth Flow', () => {
  it('should redirect to DocSend authorization URL', async () => {
    const response = await request(app).get('/auth');
    expect(response.status).toBe(302);
    expect(response.header.location).toContain('docsend.com/oauth/authorize');
  });
});

Locking It Down

Security is not just a feature, it's a must-have. Always use HTTPS in production, implement CSRF protection, and never, ever store client secrets in your codebase. Treat them like your deepest, darkest secrets!

Wrapping Up

And there you have it! You've just built a solid auth flow for your DocSend integration. Pat yourself on the back – you've laid the foundation for something great. From here, the sky's the limit. Go forth and integrate with confidence!

Remember, the auth flow is just the beginning. Now you can start playing with DocSend's API to do all sorts of cool stuff. But that's a story for another day. Keep coding, and stay awesome!