Скачать или смотреть How to Use FutureBuilder Correctly in Flutter

Learn how to effectively use `FutureBuilder` in Flutter to display asynchronous data in your app, specifically for checkbox functionality.
---
This video is based on the question https://stackoverflow.com/q/62680819/ asked by the user 'Salatgurke' ( https://stackoverflow.com/u/13111006/ ) and on the answer https://stackoverflow.com/a/62683883/ provided by the user 'camelCase1492' ( https://stackoverflow.com/u/12069830/ ) 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 do I use the FutureBuilder correctly?

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.
---
How to Use FutureBuilder Correctly in Flutter

In Flutter app development, dealing with asynchronous data is a common challenge, particularly when working with databases. One tool that can make this process simpler is the FutureBuilder. This powerful widget allows you to build a UI based on the latest snapshot of interaction with a Future — which is often tied to fetching data from a database. Today, we’ll explore how to implement FutureBuilder properly and the correct way to use the data it retrieves, especially in a scenario where we need to display a boolean value in a checkbox.

The Problem at Hand

Imagine you have a ListView in your Flutter application where you want to display whether a certain item has been obtained from your SQLite database. This process involves reading data asynchronously, which means that you cannot simply call your database fetching function and expect it to return a result immediately. You need to ensure that your UI reacts appropriately once the data is available. This is where FutureBuilder comes in handy.

The function you are using to fetch data looks like this:

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

And another function retrieves a boolean value:

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

You may find yourself puzzled when integrating this with your CheckboxListTile, leading us to the solution.

Solution: Implementing FutureBuilder Correctly

To utilize FutureBuilder, you need to ensure that you are accessing the future value in a synchronized way through its snapshot. The value from your function isObtainedDB(settings) will be saved into snapshot.data within the builder method of FutureBuilder.

1. Setting Up FutureBuilder

You can set up your FutureBuilder as follows:

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

2. Breaking Down the Code

future: The future that FutureBuilder will await for completion, which in your case is isObtainedDB(settings).

builder: A function that returns a widget based on the state of the future. Here, you check:

If data is still loading (ConnectionState.waiting), show a loading indicator.

If there’s an error, display an error message.

If everything is successful, display your CheckboxListTile.

value: snapshot.data: This is how you retrieve the boolean fetched from the database. snapshot.data holds the actual boolean value that you’ll use to set the checkbox state.

3. Handling User Interaction

The onChanged callback allows you to perform an action when the checkbox is toggled. The method setObtained(settings, value) will be called, allowing you to handle this change accordingly.

Conclusion

Using FutureBuilder is an excellent way to handle asynchronous data in Flutter applications. By following the correct setup and accessing the snapshot data appropriately, you can efficiently bind database results to UI components like a checkbox. This not only improves the user experience, ensuring smooth data handling but also keeps your code clean and maintainable. Embrace the power of FutureBuilder to enhance your Flutter projects!