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Learn how to effectively handle asynchronous data in Flutter by looping through a `Map` in a widget using `FutureBuilder`.
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This video is based on the question https://stackoverflow.com/q/74679290/ asked by the user 'Walt83' ( https://stackoverflow.com/u/20684258/ ) and on the answer https://stackoverflow.com/a/74679376/ provided by the user 'Taimoor Ghafar' ( https://stackoverflow.com/u/17082429/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Efficiently Looping a Map from an Async Method in Flutter

When working with Flutter applications, one common scenario developers encounter is the need to handle asynchronous data fetch operations. If you're dealing with a Map type that needs to be displayed in your widgets after an async method, the challenge lies in ensuring that your UI updates correctly with the data. In this post, we'll explore the problem thoroughly and provide a structured solution to looping through a Map after calling an async method.

The Problem

In your scenario, you have a method that retrieves a Map<String, String> but are unsure how to efficiently loop through this map within your widget. The direct approach you tried was placing the forEach method directly in your widget's build method. However, this isn't the cleanest or most reliable way to handle async data since the data might not be ready when the widget builds.

Initial Code Structure

Your initial method for fetching data looks like this:

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And for displaying the data, you attempted to loop through the Map directly as follows:

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

This approach has limitations because if the data isn't available yet, it could lead to unexpected behavior.

A Better Solution: Using FutureBuilder

A more elegant solution is to utilize Flutter's FutureBuilder. This widget allows you to handle asynchronous data more cleanly and provides a way to rebuild the UI based on the state of the future's result.

Step-by-Step Implementation

Define the Async Method: Prepare a method that returns a Future<Map<String, dynamic>>, simulating your data-fetching function.

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

Utilize the FutureBuilder Widget: In your build method, replace your direct data loop with FutureBuilder.

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

Explanation of the Code

FutureBuilder: It takes a future (your async data-fetching method) and a builder function that receives a snapshot of the future's state.

Connection State: Before the data arrives, we provide a CircularProgressIndicator to indicate loading.

Error Handling: If an error occurs, we display an error message.

Data Presentation: Once the data is available, we loop through the Map entries and create a list of Text widgets.

Conclusion

By using FutureBuilder, you enhance the reliability and readability of your Flutter widget when handling data obtained from asynchronous methods. This approach not only ensures your UI reflects the actual state of your data but also makes your code much cleaner and easier to maintain. Now you can present your data effectively and manage loading states without hassle!

Remember to always consider using async builders when working with network requests or time-consuming operations to improve your app's user experience.