Quick Guide to Implementing Webhooks in Expensify

Hey there, fellow Javascript devs! Ready to supercharge your Expensify integration with webhooks? Let's dive right in and get those real-time updates flowing.

Introduction

Webhooks are the secret sauce for keeping your app in sync with Expensify. They're like having a personal assistant who taps you on the shoulder whenever something important happens. No more constant polling or outdated data – just instant notifications when expenses are submitted, reports are approved, or any other crucial event occurs.

Prerequisites

Before we start cooking, make sure you've got these ingredients:

• An Expensify account with API access (you're probably already sorted here)
• A Node.js environment (because, let's face it, who doesn't love Node?)
• A basic grasp of RESTful APIs and webhooks (but don't sweat it if you're a bit rusty)

Setting Up Webhook Endpoints

First things first, let's create a simple Express server to catch those webhook events. It's like setting up a net to catch falling expenses (okay, that analogy might be a stretch, but you get the idea).

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

app.post('/webhook', (req, res) => {
  console.log('Webhook received:', req.body);
  res.sendStatus(200);
});

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

Easy peasy, right? This little server is now ready and waiting for Expensify to start throwing events its way.

Registering Webhooks with Expensify API

Now, let's tell Expensify where to send those juicy webhook events. We'll use axios because, well, it's awesome.

const axios = require('axios');

async function registerWebhook() {
  try {
    const response = await axios.post('https://integrations.expensify.com/Integration-Server/ExpensifyIntegrations', {
      type: 'create',
      credentials: 'YOUR_EXPENSIFY_CREDENTIALS',
      partnerUserID: 'YOUR_PARTNER_USER_ID',
      webhookURL: 'https://your-server.com/webhook'
    });
    console.log('Webhook registered:', response.data);
  } catch (error) {
    console.error('Error registering webhook:', error);
  }
}

registerWebhook();

Remember to replace those placeholder credentials and URLs with your actual data. No one likes a 401 Unauthorized error, trust me.

Handling Webhook Events

Alright, now that we're all set up, let's handle those incoming events like a pro. Expensify might throw a variety of events your way, so let's be ready for anything.

app.post('/webhook', (req, res) => {
  const { type, data } = req.body;

  switch(type) {
    case 'report.submitted':
      handleReportSubmitted(data);
      break;
    case 'report.approved':
      handleReportApproved(data);
      break;
    // Add more cases as needed
    default:
      console.log('Unhandled event type:', type);
  }

  res.sendStatus(200);
});

function handleReportSubmitted(data) {
  console.log('New report submitted:', data.reportID);
  // Do something cool with the submitted report
}

function handleReportApproved(data) {
  console.log('Report approved:', data.reportID);
  // Maybe send a celebratory email to the employee?
}

Securing Webhooks

Security is no joke, folks. Let's make sure those webhook events are legit by verifying their signatures.

const crypto = require('crypto');

app.post('/webhook', (req, res) => {
  const signature = req.headers['x-expensify-signature'];
  const payload = JSON.stringify(req.body);
  const expectedSignature = crypto
    .createHmac('sha256', 'YOUR_WEBHOOK_SECRET')
    .update(payload)
    .digest('hex');

  if (signature !== expectedSignature) {
    return res.status(401).send('Invalid signature');
  }

  // Process the webhook event
  // ...

  res.sendStatus(200);
});

Testing and Debugging

Testing webhooks locally can be a pain, but ngrok is here to save the day. It's like having a secret tunnel from Expensify straight to your laptop.

1. Install ngrok: npm install -g ngrok
2. Start your webhook server
3. In a new terminal, run: ngrok http 3000
4. Use the ngrok URL when registering your webhook with Expensify

Now you can debug those webhooks like a boss, right from the comfort of your local machine.

Best Practices

Here are some pro tips to keep your webhook game strong:

• Always implement idempotency. Webhook events might be sent multiple times, so make sure your code can handle that gracefully.
• Implement proper error handling and retries. The internet can be flaky sometimes.
• Log everything. Future you will thank present you when troubleshooting.

Conclusion

And there you have it! You're now armed and ready to implement webhooks in your Expensify integration. Remember, webhooks are powerful tools, so use them wisely (and have fun while you're at it).

Keep coding, stay curious, and may your expenses always be approved on the first try!