Скачать или смотреть How to Implement a Flutter HTTP Authenticator Service for OAuth2 Token Refresh

Discover how to efficiently manage OAuth2 token refresh in your Flutter app with a custom HTTP authenticator service using Dio interceptors.
---
This video is based on the question https://stackoverflow.com/q/57941368/ asked by the user 'MohdNaseem' ( https://stackoverflow.com/u/1893738/ ) and on the answer https://stackoverflow.com/a/63621224/ provided by the user 'user6264291' ( https://stackoverflow.com/u/6264291/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Flutter http authenticator service to refresh oauth2 token

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Handling OAuth2 Authentication in Flutter: Refreshing Tokens Automatically

When developing a Flutter application that requires OAuth2 authentication, one common challenge developers face is managing the expiration of access tokens. Reacting to 401 Unauthorized errors effectively can help ensure a smooth user experience. In this guide, we'll walk through how to create an authenticator service for refreshing OAuth2 tokens with the Dio HTTP client in Flutter. This guide will illustrate the method, helping you avoid needlessly repeating error handling code across multiple API calls.

Understanding the Problem

In a typical OAuth2 implementation, access tokens have a limited lifespan. When a request is made using an expired token, the server responds with a 401 Unauthorized error. In Android, libraries like OkHttp offer an Authenticator functionality, allowing developers to handle token refresh automatically during API calls.

However, in Flutter, the situation differs. Without built-in functionalities for automatic token refresh, developers must implement their solutions in a scalable way. Handling the 401 error across every API request can result in messy and repetitive code, making management cumbersome.

Solution: Using Dio Interceptor

The best way to manage token refreshes in Flutter is through Dio Interceptors. Interceptors allow you to modify requests and responses globally within your application. Here's how to set everything up:

Step 1: Add Dio Dependency

First, ensure that you have the Dio package added to your pubspec.yaml:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Create the Authenticator Service

Next, you can create an HTTP authenticator that leverages Dio's interceptor functionality to refresh tokens when a 401 error occurs. Here's an example of how to achieve this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

onRequest: This intercepts the outgoing request and attaches the current access token to the authorization header.

onResponse: This simply passes the response through without any modifications.

onError: If a 401 error is encountered, it triggers the token refresh process. The interceptor sends a request to your token refresh endpoint and updates the stored tokens if successful. Finally, it retries the original API call with the newly obtained token.

Step 3: Integrate the Authenticator into Your App

Once you have set up the authenticator service, make sure to initialize this service in your Flutter application, ensuring that all API requests utilize this logic seamlessly.

Conclusion

With this setup, you can efficiently handle OAuth2 token refresh in your Flutter app without needing to manually check for 401 errors in every API call. This not only leads to cleaner code but also enhances the user experience by keeping authentication seamless and unobtrusive.

Incorporating an authenticator service using Dio interceptors can save you valuable development time and ensure your app remains secure and responsive to API calls. Happy coding!