Скачать или смотреть Solving the flutter mobx RadioListTile Update Issue

Struggling with Flutter MobX and RadioListTiles not updating? Discover the solution to this common problem in our comprehensive guide.
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This video is based on the question https://stackoverflow.com/q/65044768/ asked by the user 'Rodrigo Lima' ( https://stackoverflow.com/u/14671052/ ) and on the answer https://stackoverflow.com/a/65047641/ provided by the user 'BambinoUA' ( https://stackoverflow.com/u/1798328/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fixing Flutter MobX RadioListTile Update Issues

When working with Flutter and MobX, developers often encounter challenges, especially regarding updating the UI based on user selection. A common issue that arises is when the RadioListTile doesn’t update the screen, leaving users puzzled. If you've found yourself facing this problem, you're not alone! Let's delve into identifying the issue and implementing a solution step by step.

Understanding the Problem

You may be trying to build a list of radio buttons using the RadioListTile widget in Flutter. However, the state is not updating as expected when a selection is made. You might see an error message stating: "No observables detected in the build method of Observer." This indicates that the MobX state management framework is not detecting changes in the observable properties in your store class.

Key Components of the Code

Before we identify the solution, let’s break down the essential parts of your code:

Main Application: This is where the UI is built, and you have defined a MyHomePage widget.

TesteStore: A MobX store responsible for holding the application's state, particularly the selected radio button value.

pubspec.yaml: This is your dependency file, ensuring all required packages are included.

The Error Message

The error message you are encountering suggests that the MobX observers do not appropriately detect the observables. Here are some steps to resolve this issue.

The Solution

Step 1: Ensure Public Access to Observables

The first tweak you should consider is ensuring that your observable variables in the TesteStore class are accessible as public members. Since you've derived TesteStore from a private class _TesteStore, MobX might not be able to detect your observables properly.

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Make sure that the class and its properties are publically accessible by not using the underscore at the beginning of the class names.

Step 2: Adjust the Observer Builder

Next, we can modify how the Observer builds its UI. Instead of directly using the observable in the Observer, try creating an intermediate variable to hold the selected value. Then use this local variable inside the builder.

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Using an intermediate variable can sometimes help with ensuring the observer correctly recognizes changes.

Step 3: Exploring ListView Alternatives

In some scenarios, using ListView instead of ListView.builder can resolve issues with state updates. Try replacing the ListView.builder with a standard ListView to see if that resolves the issue.

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Step 4: Wrapping Individual RadioListTiles

Another approach worth exploring is wrapping each RadioListTile's widget with its own Observer. By doing so, each tile becomes independently reactive, which can improve the interface's responsiveness.

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Conclusion

Building responsive Flutter applications with MobX doesn't have to be a frustrating task. By ensuring that your observables are publicly accessible, using intermediate assignments, exploring alternative list structures, and properly wrapping widgets in Observer, you can resolve many common issues with state updates. If you’re still facing challenges, consider revisiting the setup and dependencies in your pubspec.yaml file. Happy coding!