How To Create a Dynamic Search Bar in Flutter

As you may know, Flutter is known for its intuitiveness and ease of use. One of my favourite features is the onChanged functionality, which lets you create dynamic and efficient user interfaces with minimal code. Particularly, I tend to use it to create search bars that update results dynamically as you type.

Why onChanged is Cool

1. Real-Time Updates: onChanged automatically triggers the given function every time the text in TextField changes.

2. Minimal Code Overhead:In many programming languages, setting up a dynamic search bar often requires multiple steps, like adding listeners, boilerplate code, managing debouncing and handling input. Flutter’s onChanged functionality handles this with just one line of code; it is an accessible and elegant solution.

3. Efficient Resource Use: Because onChanged works with Flutter’s state management, it allows us to handle search queries and UI updates with minimal resource consumption. This reduces unnecessary processing, as onChanged ensures the state only updates when a user changes the text input, keeping the app’s memory and processing needs low. No need to make a billion HTTP requests!

4. Better User Experience: results being updated in real-time makes your app feel responsive and interactive.

Here is how I implement it:

Add onChanged: _filterUsernames, in the TextField, then define the function as below.

// Function to update search results by filtering input
void _filterUsernames(String query) {
    setState(() {
      filteredUsers = dummyUsers
          .where((user) =>
              user['username']!.toLowerCase().startsWith(query.toLowerCase()))
          .toList();
    });
  }

Check out my full solution in my gist.