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Discover how to gracefully handle API status codes with FutureOr and AutoDisposeAsyncNotifier in Riverpod 2.0, while simplifying your Flutter application.
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This video is based on the question https://stackoverflow.com/q/77164102/ asked by the user 'J. O'Ryan' ( https://stackoverflow.com/u/7483930/ ) and on the answer https://stackoverflow.com/a/77164255/ provided by the user 'Randal Schwartz' ( https://stackoverflow.com/u/22483/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Handling API Status Codes in Riverpod 2.0: A Comprehensive Guide

If you're diving into Riverpod for the first time, you may encounter challenges, especially when managing API requests and handling their status codes. In this guide, we'll break down how to effectively manage API status codes using FutureOr and the AutoDisposeAsyncNotifier in Riverpod 2.0. By the end of this guide, you'll have the knowledge you need to implement graceful error handling and improve the reliability of your Flutter applications.

Understanding the Challenges with API Calls

When working with APIs, it's essential to consider the variety of potential responses your application may encounter. Typical challenges include:

Successful responses: Where the status code is 200, and the data is returned as expected.

Error responses: These might include various status codes, such as 404 Not Found or 500 Internal Server Error, where the data is not returned or is misleading.

Loading state: While waiting for a response, it's important to provide feedback to users, generally through a loading indicator.

In the example provided, the login function fails to handle cases where the API returns a status other than 200. Let's explore how to manage this correctly.

Structuring Your Code for Better Error Handling

To handle API calls effectively in Riverpod, you'll need to categorize your AsyncNotifier methods as follows:

Infrastructure (build method) – Responsible for the initial state of your API call.

External mutators (public API) – Methods available for components outside of your class to invoke actions.

Internal helpers – Frequently called methods that execute logic internally but should not directly modify the state observable.

Implementing the Login Function

In the specific case of the login function, here’s how you can restructure the code:

Change the return type of login method: Update it to return a Future<void>, allowing for better control over async execution.

Create an internal helper: Introduce an internal _login function that performs the heavy lifting of making the API request and returning the user data or throwing an error based on the response.

Updated Code Structure

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Utilizing the Results in Your UI

With the above structure, you can easily handle the different states in your UI using a switch statement:

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This effectively handles the loading state, successful responses, and errors.

Conclusion

Handling API status codes does not have to be cumbersome. By strategically structuring your provider methods and properly managing the async states, you can create a robust login feature or any other API-dependent functionality in your Flutter application.

This approach can be expanded further, but mastering these initial steps will significantly improve your development experience using Riverpod 2.0. Happy coding!