Скачать или смотреть Updating Your getIt Instance in Flutter

Learn how to effectively update a `getIt` instance in Flutter when using the Dio library for API requests. This guide covers everything you need to know to manage instances and tokens in your application.
---
This video is based on the question https://stackoverflow.com/q/73134348/ asked by the user 'Ankit' ( https://stackoverflow.com/u/11678970/ ) and on the answer https://stackoverflow.com/a/73134417/ provided by the user 'BosS' ( https://stackoverflow.com/u/10170295/ ) 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: How to update a get it instance in flutter?

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.
---
Updating Your getIt Instance in Flutter: A Simple Guide

When developing applications in Flutter, particularly when working with dependencies like APIs, you might find yourself grappling with how to update certain instances or tokens dynamically. One common scenario arises when using the getIt package along with Dio, a powerful HTTP client for Dart. This post will guide you through the process of updating an instance in getIt, addressing a common issue encountered by many developers.

The Problem

In your application, you've set up instances using the getIt package, which is great for managing dependencies. Your implementation initializes a DioFactory instance, which in turn creates a Dio instance necessary for making network requests. However, you encounter a problem: when you change a token value mid-application, the changes do not reflect in the Dio instance that was registered as a singleton.

Example Situation

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

When the application is built for the first time, your Constants.token has a blank value. As your application runs, you change this token, but the requests still show the old, empty token in the authorization header.

The Solution

To resolve this issue, you will need to register your Dio instance with registerFactory instead of registerLazySingleton. The difference is that registerFactory creates a new instance every time it is requested, allowing you to update parameters such as your token dynamically.

Step-by-Step Solution

Change the Registration Method:
Instead of registering your Dio instance as a lazy singleton, change your registration to use registerFactory. This ensures every time you call for this instance, you get a fresh instance with the updated token. Here's how you can do it:

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

Modify the getDio Method:
Ensure that your getDio function is capable of using the current value of the token whenever it is called. The original getDio setup should work as intended without changes since it retrieves the token value directly within the function.

Fetching the Updated Token:
Implement a mechanism to update the token whenever it changes in your application. This way, every time you need to make an API call, you can fetch the latest instance of Dio, which includes the updated token:

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

Conclusion

By switching from registerLazySingleton to registerFactory, you create a new instance of Dio each time it's requested, allowing you to update important parameters like the authorization token on the fly. This approach not only solves the problem of token updates but also enhances the flexibility of your dependency injection setup.

With this guide, you should now feel confident in managing your getIt instances in Flutter, particularly when dealing with changes that occur as your application runs. Happy coding!