Implementing Infinite Scroll Pagination in Flutter: A Step-by-Step Guide

Mastering Infinite Scroll Pagination in Flutter

Infinite scroll pagination is a powerful technique for loading data in chunks as users scroll through your app. This approach enhances the user experience by reducing load times and improving overall performance. In this article, we’ll explore how to implement infinite scroll pagination in Flutter using three different methods: building from scratch with ListView, utilizing ScrollController, and leveraging the infinitescrollpagination package.

Understanding Infinite Scroll Pagination

Infinite scroll pagination involves loading data in segments as users scroll through your app. This technique is particularly useful when dealing with large datasets, as it prevents overwhelming the user with too much information at once. By loading data in chunks, you can improve the overall performance of your app and reduce the risk of crashes.

Building from Scratch with ListView

To build an infinite scroll pagination system from scratch, you’ll need to create a ListView that loads data in chunks as the user scrolls. Here’s a basic example of how to achieve this:

“`dart
class PostOverviewScreen extends StatefulWidget {
@override
_PostOverviewScreenState createState() => _PostOverviewScreenState();
}

class _PostOverviewScreenState extends State {
final _posts = [];
bool _isLastPage = false;
int _pageNumber = 0;
bool _error = false;
bool _loading = false;

@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(‘Infinite Scroll Pagination’),
),
body: loading
? Center(
child: CircularProgressIndicator(),
)
: _error
? Center(
child: Text(‘Error loading data’),
)
: ListView.builder(
itemCount: _posts.length,
itemBuilder: (context, index) {
if (index == _posts.length – 1 && !isLastPage) {
loadMorePosts();
}
return PostItem(posts[index]);
},
),
);
}

Future loadMorePosts() async {
setState(() {
_loading = true;
});
try {
final response = await http.get(Uri.parse(‘https://jsonplaceholder.typicode.com/posts?page=${pageNumber + 1}&limit=10′));
final jsonData = jsonDecode(response.body);
setState(() {
_posts.addAll(jsonData.map((post) => Post.fromJson(post)).toList());
_isLastPage = jsonData.length < 10;
_pageNumber++;
_loading = false;
});
} catch (e) {
setState(() {
_error = true;
_loading = false;
});
}
}
}
“`

Utilizing ScrollController

Another way to implement infinite scroll pagination is by utilizing ScrollController. This approach allows you to track the scroll position of the user and load more data when they reach the end of the list.

“`dart
class PostOverviewScreen extends StatefulWidget {
@override
_PostOverviewScreenState createState() => _PostOverviewScreenState();
}

class _PostOverviewScreenState extends State {
final _scrollController = ScrollController();
final _posts = [];
bool _isLastPage = false;
int _pageNumber = 0;
bool _error = false;
bool _loading = false;

@override
void initState() {
super.initState();
scrollController.addListener(onScroll);
}

@override
void dispose() {
_scrollController.dispose();
super.dispose();
}

@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(‘Infinite Scroll Pagination’),
),
body: loading
? Center(
child: CircularProgressIndicator(),
)
: _error
? Center(
child: Text(‘Error loading data’),
)
: ListView.builder(
controller: _scrollController,
itemCount: _posts.length,
itemBuilder: (context, index) {
return PostItem(posts[index]);
},
),
);
}

void onScroll() {
if (scrollController.offset >= scrollController.position.maxScrollExtent * 0.8 && !isLastPage) {
_loadMorePosts();
}
}

Future loadMorePosts() async {
setState(() {
_loading = true;
});
try {
final response = await http.get(Uri.parse(‘https://jsonplaceholder.typicode.com/posts?page=${pageNumber + 1}&limit=10′));
final jsonData = jsonDecode(response.body);
setState(() {
_posts.addAll(jsonData.map((post) => Post.fromJson(post)).toList());
_isLastPage = jsonData.length < 10;
_pageNumber++;
_loading = false;
});
} catch (e) {
setState