Скачать или смотреть Solving the DropdownButton Selection Display Issue in Flutter

Learn how to fix the problem where selected items in a `DropdownButton` are not displayed correctly in Flutter. This guide provides a clear, step-by-step solution to ensure your dropdown selections show up properly.
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This video is based on the question https://stackoverflow.com/q/72151536/ asked by the user 'Max' ( https://stackoverflow.com/u/10830211/ ) and on the answer https://stackoverflow.com/a/72152534/ provided by the user 'AJ-' ( https://stackoverflow.com/u/2374769/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving the DropdownButton Selection Display Issue in Flutter

As a Flutter developer, you might face situations where your DropdownButton fails to display the selected items correctly. This can be frustrating, especially when you’re trying to enhance the user experience in your application. In this guide, we’ll explore this issue and provide a straightforward solution to ensure that selected items are visible in your dropdown button.

The Problem: Missing Selected Value in DropdownButton

When using a DropdownButton along with CheckboxListTile, you might encounter a bug where the selected items do not display in the button itself, although they appear in the dropdown list. This can lead to confusion for users as they may think that their selections have not been registered.

What the Code Looks Like

Here’s a snippet from a sample implementation of a DropdownButton tied to checkboxes:

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

Despite setting up the state management correctly, the dropdown button fails to reflect any selected value, which is the crux of our problem.

The Solution: Using PopupMenuButton

To effectively address this issue, we can switch to using a PopupMenuButton. This approach not only resolves the display problem but also enhances the user interface.

Step-by-Step Implementation

Setting Up the Popup Menu

You’ll replace your DropdownButton with a PopupMenuButton. Here's how you can structure it:

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

Managing Selections with State

Ensure to manage selected items in _selectedTitles just like before using _onItemSelect. Additionally, here’s a method to allow users to select or unselect all items:

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

Example of All Selection

You can also extend the dropdown features by enabling users to select all or none of the options easily. Here's how to render it within the item builder:

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

Conclusion

By switching to a PopupMenuButton, you can effortlessly resolve the issue of selected items not being displayed in a dropdown button. This method not only fixes the problem but also enhances the user interaction by providing additional functionality like selecting all or clearing selections.

Try implementing this solution in your Flutter application, and enjoy a smoother, more user-friendly dropdown experience!