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

Aug 11, 2024 • 7 minute read

Hey there, fellow JavaScript enthusiast! Ready to dive into the world of Todoist integrations? Today, we're going to tackle one of the most crucial parts 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 and get you up and running in no time.

Introduction

Todoist's API is a powerful tool that allows us to tap into their task management ecosystem. But before we can start creating tasks and managing projects, we need to ensure our integration is secure and authorized. That's where the auth flow comes in. It's like the bouncer at an exclusive club – making sure only the right people (or in our case, applications) get access.

Prerequisites

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

A Todoist Developer account (it's free, so no excuses!)
Node.js and Express.js set up on your machine
A basic understanding of OAuth 2.0 (don't sweat it if you're rusty, we'll cover the essentials)

Setting up the project

First things first, let's get our project set up:

Head over to the Todoist Developer Console and create a new app.
Grab your client ID and client secret – these are your VIP passes to the Todoist API.

Implementing the authorization flow

Step 1: Redirect to Todoist authorization page

We're going to start by sending our users to Todoist's authorization page. Here's how:

const authUrl = `https://todoist.com/oauth/authorize?client_id=${clientId}&scope=task:add,data:read&state=${state}`;
res.redirect(authUrl);

Make sure to replace ${clientId} with your actual client ID and generate a unique ${state} for CSRF protection.

Step 2: Handling the callback

Once the user grants permission, Todoist will redirect them back to your specified callback URL with an authorization code. Let's grab that code:

app.get('/callback', async (req, res) => {
  const { code, state } = req.query;
  // Verify state to prevent CSRF attacks
  if (state !== expectedState) {
    return res.status(400).send('Invalid state parameter');
  }
  
  // Exchange code for access token
  const tokenResponse = await axios.post('https://todoist.com/oauth/access_token', {
    client_id: clientId,
    client_secret: clientSecret,
    code: code,
    grant_type: 'authorization_code'
  });
  
  const accessToken = tokenResponse.data.access_token;
  // Store the access token securely
});

Step 3: Storing and using the access token

Now that we have the access token, we need to store it securely. Consider using encrypted storage or a secure database. With the token in hand, you can make authenticated requests to the Todoist API:

const response = await axios.get('https://api.todoist.com/rest/v2/tasks', {
  headers: {
    'Authorization': `Bearer ${accessToken}`
  }
});

Error handling and edge cases

Don't forget to handle potential errors and edge cases:

Implement proper error handling for API requests
Set up token refresh mechanisms to keep your integration running smoothly

Security considerations

Security is paramount when dealing with user data. Always:

Use HTTPS for all communications
Implement the state parameter to prevent CSRF attacks
Store tokens securely, preferably encrypted

Testing the integration

Before you pop the champagne, make sure to thoroughly test your integration:

Try the auth flow yourself
Test with different user accounts
Implement automated tests for your auth flow

Conclusion

And there you have it! You've successfully implemented the authorization flow for your Todoist integration. Pat yourself on the back – you're one step closer to building an awesome productivity tool.

Remember, this is just the beginning. With the auth flow in place, you can now explore the full potential of the Todoist API. The sky's the limit!

Additional resources

Want to dive deeper? Check out these resources:

Now go forth and build something amazing! And remember, if you get stuck, the developer community is always here to help. Happy coding!