Скачать или смотреть How to Avoid Page Refresh for Data Fetching in Flutter's ListView Using StreamBuilder

Discover how to efficiently update your Flutter ListView without the need for page refreshes by using StreamBuilder for real-time data fetching from Firebase.
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This video is based on the question https://stackoverflow.com/q/73558237/ asked by the user 'Irfan Ganatra' ( https://stackoverflow.com/u/18817235/ ) and on the answer https://stackoverflow.com/a/73558337/ 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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Avoiding Page Refresh for Data Fetching in Flutter's ListView

Flutter provides robust tools for building beautiful applications, but developers often run into issues when trying to efficiently fetch and display data, particularly when using ListView.builder. A common dilemma developers face is how to refresh the ListView to display data fetched from a database like Firebase without needing to manually refresh the page. In this post, we will explore how to solve this problem using StreamBuilder—a powerful widget in Flutter that makes asynchronous data handling easier and more efficient.

The Problem: Fetching Data Inefficiently

In the code snippet shared by our user, the issue arises when data is fetched from a Firebase collection but doesn't appear in the ListView unless the page is refreshed. Here's a brief overview of the existing code:

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

Why This Happens

The key issue in this implementation is that the getusers function is called inside the build method. This leads to the following concerns:

Unnecessary Calls: Every time the widget rebuilds, it makes a fresh call to the database, which is inefficient and can lead to performance issues.

Empty Data State: If the data isn't fetched yet, the ListView will attempt to build itself using an empty list, leading to the user not seeing any data until they refresh the page.

The Solution: Using StreamBuilder

To effectively handle data fetching and ensure that our UI is responsive to data changes without manual refreshes, we can use StreamBuilder. This widget listens for updates in the Firestore collection and rebuilds the UI automatically when new data is available.

Implementing StreamBuilder

Here is how to refactor the above code using StreamBuilder for better data handling:

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

Breakdown of the Code

Creating a Stream: The line final myStream = FirebaseFirestore.instance.collection("users").snapshots(); creates a stream that listens to changes in the "users" collection. Anytime data changes, the stream sends updates to the StreamBuilder.

Using StreamBuilder: Inside the build method, we create a StreamBuilder that listens to the changes from myStream.

Handling Data and Loading States:

If the snapshot has data (snapshot.hasData), we populate the ListView.builder with the documents obtained from the database.

If the data is still loading, a CircularProgressIndicator is shown, keeping the user informed of the loading status.

Benefits of Using StreamBuilder

Real-Time Updates: With StreamBuilder, your UI updates instantly as soon as data in Firestore changes.

Performance: The app doesn't need to reload data unnecessarily, making it more efficient.

User Experience: By showing a loading indicator, the app improves user experience by clearly indicating that data is being loaded.

Conclusion

By switching from a manual data-fetching approach to utilizing StreamBuilder, we can enhance the efficiency and responsiveness of our Flutter applications. This not only helps eliminate the need for manual page refreshes but also ensures that users always see the latest data as soon as it becomes available. Happy coding!