How to Reset State of a Sibling Widget in Flutter

Описание: Learn how to reset the state of a `DropdownButton` from a sibling class in Flutter using parent callbacks, providing a practical solution for managing widget states seamlessly.
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This video is based on the question https://stackoverflow.com/q/71580020/ asked by the user 'Thoxh' ( https://stackoverflow.com/u/12897582/ ) and on the answer https://stackoverflow.com/a/71580087/ provided by the user 'ulmas' ( https://stackoverflow.com/u/10678150/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Reset State of a Sibling Widget in Flutter

In Flutter, managing the state of widgets can sometimes be tricky, especially when dealing with sibling widgets. One common scenario is when you have a DropdownButton that needs to reset its value when another widget, such as a button, is pressed. In this guide, we explore how to achieve this by leveraging parent-child communication through callback functions.

The Problem

Let's consider a situation where you have two sibling widgets contained within a parent widget: a DropdownButton and a button. The requirement is to reset the value of the dropdown when the button is pressed. Sounds straightforward, right? However, passing state between siblings directly isn't possible in Flutter, and this can lead to confusion for developers.

Example Scenario

In our example, we have:

A Stackoverflow class that houses our dropdown functionality.

A SomeButton class that will trigger the reset of the dropdown's value.

Current State of the Code

Here's a simplified version of how the existing structure looks:

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

As you can see, there's no clear way for the SomeButton class to inform the Stackoverflow class to reset its dropdownValue.

The Solution

The best approach to solve this problem is to lift the state up to the parent widget (Parent) and use callback functions. Here is how you can accomplish this:

Step 1: Update the Parent Class

Transform the Parent class into a StatefulWidget, where you'll store the state (dropdownValue). You will also define a callback method to update this value from the SomeButton class.

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

Step 2: Pass the Callback and Value

Next, modify the constructors of the Stackoverflow and SomeButton classes to accept the dropdownValue and the callback.

Stackoverflow Class Modification

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

SomeButton Class Modification

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

Conclusion

By lifting the state up to the Parent class and using callback functions, we can effectively reset the state of the DropdownButton from another sibling widget (SomeButton). This method not only allows for better state management but also keeps your code clean and organized.

Give this approach a try in your Flutter applications, and you'll be more confident in handling state across sibling widgets. Happy coding!