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Infinite Scroll Pagination

Unopinionated, extensible and highly customizable package to help you lazily load and display small chunks of data as the user scrolls down the screen – known as infinite scrolling pagination, endless scrolling pagination, auto-pagination, lazy loading pagination, progressive loading pagination, etc.

Designed to feel like part of the own Flutter framework.

Example Project

Tutorial

By raywenderlich.com (step-by-step, hands-on, in-depth and illustrated).

Usage

class CharacterListView extends StatefulWidget {
  @override
  _CharacterListViewState createState() => _CharacterListViewState();
}

class _CharacterListViewState extends State<CharacterListView> {
  static const _pageSize = 20;

  final PagingController<int, CharacterSummary> _pagingController =
      PagingController(firstPageKey: 0);

  @override
  void initState() {
    _pagingController.addPageRequestListener((pageKey) {
      _fetchPage(pageKey);
    });
    super.initState();
  }

  Future<void> _fetchPage(int pageKey) async {
    try {
      final newItems = await RemoteApi.getCharacterList(pageKey, _pageSize);
      final isLastPage = newItems.length < _pageSize;
      if (isLastPage) {
        _pagingController.appendLastPage(newItems);
      } else {
        final nextPageKey = pageKey + newItems.length;
        _pagingController.appendPage(newItems, nextPageKey);
      }
    } catch (error) {
      _pagingController.error = error;
    }
  }

  @override
  Widget build(BuildContext context) => 
      // Don't worry about displaying progress or error indicators on screen; the 
      // package takes care of that. If you want to customize them, use the 
      // [PagedChildBuilderDelegate] properties.
      PagedListView<int, CharacterSummary>(
        pagingController: _pagingController,
        builderDelegate: PagedChildBuilderDelegate<CharacterSummary>(
          itemBuilder: (context, item, index) => CharacterListItem(
            character: item,
          ),
        ),
      );

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

For more usage examples, please take a look at our cookbook or check out the example project.

Features

API Overview

API Diagram

Motivation

Flutter indeed makes our job way easier than other toolkits when talking about infinite scrolling. It's when we combine that with automated pagination and status indicators that things get complicated.

ListView.builder builds your items on demand, but it doesn't help you with fetching them or displaying status indicators.

Your listing will go through several stages: first page loading, first page error, subsequent page loading, subsequent page error, empty list and completed list. Infinite Scroll Pagination takes care of orchestrating between them, rendering each one and letting you know when more data is needed.

Libraries

infinite_scroll_pagination