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Learn how to leverage `FutureBuilder` in Flutter to dynamically change widgets based on the result of asynchronous operations.
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This video is based on the question https://stackoverflow.com/q/75356821/ asked by the user 'Tony Lam' ( https://stackoverflow.com/u/20622797/ ) and on the answer https://stackoverflow.com/a/75356857/ provided by the user 'Md. Yeasin Sheikh' ( https://stackoverflow.com/u/10157127/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Return Different Widgets Based on Future Values in Flutter

When developing Flutter applications, you'll often find yourself needing to display different widgets based on asynchronous data. A common scenario arises when you want to show different icons based on a Future<bool> value. For example, you might want to toggle between a filled heart icon for a favorite item and an outlined heart icon for an item that isn't favored.

In this guide, we'll unravel how to effectively manage asynchronous calls in Flutter using FutureBuilder. We’ll dive into a step-by-step explanation, illustrating how this can be accomplished through code snippets and clear examples.

Understanding the Problem

You might be working on a mobile application where hypothetically displaying a list of items requires showing whether each item is a favorite or not. To achieve this, the app needs to determine the favorite status of each item by querying a backend or local data source asynchronously, returning a boolean value.

Here's a brief summary of what is typically required:

You want to display a list of items.

Each item should show an icon based on its favorite status.

The favorite status is determined by an asynchronous operation.

The Solution: Using FutureBuilder

The most efficient way to handle asynchronous data in Flutter is by using the FutureBuilder widget. This widget helps manage the lifecycle of an asynchronous operation, providing various states such as loading, success, and error. It automatically rebuilds its child when the future resolves, simplifying state management.

Here's how to implement it step-by-step:

Step 1: Refactor setFavouriteIcon

Instead of directly attempting to handle the Future value in your widget, you encapsulate the logic within a FutureBuilder. Here’s how this can be structured:

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

Step 2: Use setFavouriteIcon in Your List

Integrate the setFavouriteIcon method within the ListView.builder. Here’s how you can utilize it within your data card layout:

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

Conclusion

By using FutureBuilder, you ensure that your widget efficiently handles asynchronous loading states and dynamically rebuilds based on the received data. This not only simplifies your code structure but significantly improves user experience by providing responsive UI elements.

As you plot your journey through Flutter development, remember that effective data management techniques like FutureBuilder play a critical role in handling future values and displaying corresponding widgets.

Feel free to explore and adapt this method to suit your Flutter projects for a more robust and interactive user interface!