Mastering the Search Feature in Flutter: A Complete Guide to SearchDelegate and ListView with a Top AppBar Search Bar

When building user-friendly Flutter applications, adding a robust search functionality enhances user experience significantly. Flutter’s SearchDelegate makes it easy to implement a search feature with a customizable UI and functionality. In this guide, we’ll create a CustomSearchDelegate to demonstrate how to implement a simple search bar that filters a list of country names.

What Is SearchDelegate?

SearchDelegate is a class provided by Flutter for creating search interfaces. It offers out-of-the-box methods to customize search actions, suggestions, and results.

Search Actions (buildActions)
This method defines the widgets displayed on the right side of the search bar. In this example, a clear button is included to reset the search query.

IconButton(
  icon: const Icon(Icons.clear),
  onPressed: () {
    if (query.isEmpty) {
      close(context, null);
    } else {
      query = '';
    }
  },
)

Leading Icon (buildLeading)
The buildLeading method defines the widget on the left side of the search bar. Here, it’s an arrow-back icon that closes the search interface.

IconButton(
  icon: const Icon(Icons.arrow_back),
  onPressed: () {
    close(context, null);
  },
)