How to Filter JSON Data in Flutter Using a Text Field

Discover how to filter JSON data in Flutter dynamically with a Text Field input. Learn step-by-step how to create an engaging patient list from a web service!
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This video is based on the question https://stackoverflow.com/q/66597596/ asked by the user 'mvasco' ( https://stackoverflow.com/u/2665223/ ) and on the answer https://stackoverflow.com/a/66597774/ provided by the user 'DNS' ( https://stackoverflow.com/u/3177054/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Filter JSON Data in Flutter Using a Text Field

Do you have a list of data pulled from a web service in your Flutter application and want to allow users to filter through it? In this post, we will walk you through how to efficiently filter JSON data displayed in a ListView based on user input in a TextField. You'll learn to implement a simple yet effective search feature that enhances user experience. Let’s dive in!

Understanding the Problem

You're building a Flutter application that fetches a list of patients in JSON format from a web service and displays them in a ListView widget. To improve accessibility and functionality, you want to enable users to filter this list dynamically based on a search string entered in a TextField. The challenge lies in how to effectively filter these JSON data based on that input while maintaining performance and responsiveness.

The Solution

To tackle this problem, you can make use of the TextEditingController class, which allows you to listen for changes in the TextField and update your ListView accordingly. Let’s break down the solution into clear steps.

Step 1: Set Up Your TextEditingController

First, create an instance of TextEditingController. This controller will help you access the user input in the TextField.

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Step 2: Listen for Changes

In your initState method, add a listener to your TextEditingController to monitor changes. When the user types in the TextField, this listener will trigger the filter function.

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Step 3: Create the TextField

Use the TextEditingController in your TextField to capture user input. Update your TextField widget to reference this controller.

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Step 4: Implementing the Filtering Logic

You will need to implement a filtering function that will compare user input against the data received from the API. For demonstration, you can write a method _filterList and iterate through your original list of patients.

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Step 5: Show Filtered Results

Update your ListView logic to consider the filtered list once the user modifies the search string.

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Final Code Snippet

Here’s how your complete widget might look like, incorporating all the above elements:

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Conclusion

In this article, we explored how to filter JSON data in Flutter using a TextField. We set up a TextEditingController, listened for input changes, and filtered our patient list accordingly. This functionality greatly enhances the user experience by allowing users to quickly find the information they need. Give it a try in your next Flutter project to see the difference it makes!

Feel free to reach out if you have any questions or need further clarification on any of the steps. Happy coding!

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