Paginable is a Flutter package which makes pagination easier.

Paginable Widgets

• PaginableListViewBuilder is paginable's version of ListView.builder
• PaginableCustomScrollView is paginable's version of CustomScrollView
• PaginableSliverChildBuilderDelegate is paginable's version of SliverChildBuilderDelegate

Usage

Using PaginableListViewBuilder

As I mentioned earlier, this widget is just a paginable's version of ListView.builder which provides only three more parameters.

class Home extends StatelessWidget {
  const Home({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Scaffold(
        appBar: AppBar(
          title: const Text('PaginableListViewBuilder'),
        ),
        body: PaginableListViewBuilder(
            loadMore: () async {},
            errorIndicatorWidget: (exception, tryAgain) => Container(
                  color: Colors.redAccent,
                  height: 130,
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Text(
                        exception.toString(),
                        style: const TextStyle(fontSize: 16),
                      ),
                      const SizedBox(
                        height: 16.0,
                      ),
                      ElevatedButton(
                        style: ButtonStyle(
                          backgroundColor:
                              MaterialStateProperty.all(Colors.green),
                        ),
                        onPressed: tryAgain,
                        child: const Text('Try Again'),
                      ),
                    ],
                  ),
                ),
            progressIndicatorWidget: const SizedBox(
              height: 100,
              child: Center(
                child: CircularProgressIndicator(),
              ),
            ),
            itemBuilder: (context, index) => ListTile(
                  leading: CircleAvatar(
                    child: Text(
                      index.toString(),
                    ),
                  ),
                ),
            itemCount: 20),
      ),
    );
  }
}

• loadMore takes an async function which will be executed when the scroll is almost at the end.
• errorIndicatorWidget also takes a function which contains two parameters, one being of type Exception and other being a Function(), returning a widget which will be displayed at the bottom of the scrollview when an exception occurs in the async function which we passed to the loadMore parameter. The parameter with type Exception will contain the exception which occured while executing the function passed to the parameter loadMore if exception occured and the parameter with type Function() will contain the same function which we passed to the loadMore parameter.
• progressIndicatorWidget takes a widget which will be displayed at the bottom of the scrollview to indicate the user that the async function we passed to the loadMore parameter is being executed.

Using PaginableCustomScrollView with PaginableSliverChildBuilderDelegate

Paginable also supports SliverList, but instead of using CustomScrollView one need to use PaginableCustomScrollView along with PaginableSliverChildBuilderDelegate as the delegate.

class Home extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Scaffold(
        body: PaginableCustomScrollView(
          loadMore: () async {},
          slivers: [
            const SliverAppBar(
              title: Text('PaginableSliverChildBuilderDelegate'),
              floating: true,
            ),
            SliverList(
              delegate: PaginableSliverChildBuilderDelegate(
                (context, index) => ListTile(
                  leading: CircleAvatar(
                    child: Text(
                      index.toString(),
                    ),
                  ),
                ),
                childCount: 20,
                errorIndicatorWidget: (exception, tryAgain) => Container(
                  color: Colors.redAccent,
                  height: 130,
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Text(
                        exception.toString(),
                        style: const TextStyle(fontSize: 16),
                      ),
                      const SizedBox(
                        height: 16.0,
                      ),
                      ElevatedButton(
                        style: ButtonStyle(
                          backgroundColor:
                              MaterialStateProperty.all(Colors.green),
                        ),
                        onPressed: tryAgain,
                        child: const Text('Try Again'),
                      ),
                    ],
                  ),
                ),
                progressIndicatorWidget: const SizedBox(
                  height: 100,
                  child: Center(
                    child: CircularProgressIndicator(),
                  ),
                ),
              ).build(),
            ),
          ],
        ),
      ),
    );
  }
}

You might miss that the parameter loadMore is in PaginableCustomScrollView, the rest two errorIndicatorWidget & progressIndicatorWidget are in PaginableSliverChildBuilderDelegate and we are calling build() on PaginableSliverChildBuilderDelegate. It is mandatory to call build() on PaginableSliverChildBuilderDelegate because it returns a SliverChildBuilderDelegate.

It is worth noting that Paginable is only resposible for executing the async function passed to the loadMore parameter when the scroll is almost at the end, displaying errorIndicatorWidget at the bottom of the scrollview when an exception occurs in the loadMore and displaying progressIndicatorWidget at the bottom of the scrollview to indicate the user that the loadMore is being executed.

Paginable is not resposible for managing states, to know about different ways of managing states in Flutter, https://flutter.dev/docs/development/data-and-backend/state-mgmt/options

Contribution

If you would like to contribute to the package (e.g. by improving the documentation, solving a bug or adding a cool new feature), you are welcomed and very much appreciated to send us your pull request and if you find something wrong with the package, please feel free to open an issue.