Скачать или смотреть Troubleshooting Flutter Chopper Swagger API Endless Request Loop: How I Resolved It

Learn how to fix an endless request loop in your Flutter application using Chopper with Swagger documentation. Explore common issues and solutions for seamless API communication.
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This video is based on the question https://stackoverflow.com/q/76710461/ asked by the user 'Haissem55' ( https://stackoverflow.com/u/12287148/ ) and on the answer https://stackoverflow.com/a/76735538/ provided by the user 'Haissem55' ( https://stackoverflow.com/u/12287148/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting Flutter Chopper Swagger API Endless Request Loop: How I Resolved It

When working on Flutter applications, setting up API communication can sometimes lead to frustrating challenges. One particularly common issue arises when using Chopper along with Swagger documentation, resulting in an endless loop of requests. In this post, we’ll explore how to identify and fix this problem based on real-world experiences.

The Problem Setup

While attempting to interface a Flutter client with a NestJS server using Swagger documentation, many developers report encountering a peculiar situation:

The Flutter client successfully sends requests to the server, which processes them correctly—evidenced by thorough testing through tools like Postman.

However, instead of receiving the expected response, the client perpetually resends the request, creating an infinite loop.

Interestingly, there are no errors or exceptions logged to pinpoint what’s gone wrong. This raises the question: Could some misconfiguration or unchecked behavior within the code be responsible?

My Experience

In my case, I was working on setting up a connection to a NestJS server. After generating API code using the swagger_dart_code_generator, I found that whenever I called any API function, it would lead to this endless request issue.

At first, it felt confusing—especially since everything looked right at a glance. But as I delved deeper, the solution turned out to be rooted in the way I handled authentication.

Identifying the Cause

After various trials, I discovered the source of the issue was related to the Authenticator implementation in my Flutter app. More specifically, the authenticate method was repeatedly returning a request, which led Chopper to attempt to resend it without a valid reason.

Here’s What I Found:

Existing Authenticator Behavior: The original MyAuthenticator was designed to always return a request, even in situations where a valid authentication response wasn't provided. This would trigger Chopper to repeatedly try sending the same request.

Error Handling: The lack of an appropriate response for cases other than unauthorized access led to the infinite loop. Understanding this allowed me to refactor the authenticate method to only proceed under specific circumstances.

The Solution

Here’s how I adjusted the MyAuthenticator class to break the endless request cycle:

Revised MyAuthenticator Code

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

Key Changes Implemented

The method now only returns the modified request if the response indicates unauthorized access.

For all other status codes, I return null, signaling Chopper that there's no need to send the request again.

Conclusion

By effectively modifying the MyAuthenticator to handle only exceptional cases and return null otherwise, I successfully resolved the infinite request loop issue in my Flutter app using the Chopper client. If you encounter a similar problem, consider reviewing your authentication logic, as it often plays a crucial role in API requests and their handling.

When dealing with APIs, thorough testing, debugging, and understanding the underlying frameworks are pivotal in ensuring seamless interactions between your client and server. Happy coding!