📜 listview_utils

Superchange ListView with custom adapters to add infinite scrolling.

Example

CustomListView(
  loadingBuilder: CustomListLoading.defaultBuilder,
  itemBuilder: (context, index, item) {
    return ListTile(
      title: Text(item['title']),
    );
  },
  adapter: NetworkListAdapter(
    url: 'https://jsonplaceholder.typicode.com/posts',
    limitParam: '_limit',
    offsetParam: '_start',
  ),
);

Migration guide from 0.1.X to 0.2.Y

children property removed

If you want to use children property with CustomListView, I suggest you to use flutter's own ListView component instead. We wanted to focus on dynamic sources rather than static ones.

onErrorBuilder property type changed

CustomListView(
  onErrorBuilder: (context, details, listView) {
    // Print throwed exception to console
    print(details.error);
  },
)

CustomListView(
  onErrorBuilder: (context, error, listView) {
    // Print throwed exception to console
    print(error);
  },
)

onLoadMore property deprecated

You need to convert custom data source handlers to list adapters. Here's simple example how to implement your own list adapter.

class MyListAdapter implements BaseListAdapter {
  const MyListAdapter(this.url);
  
  final String url;

  @override
  Future<ListItems> getItems(int offset, int limit) async {
    // To handle errors using `errorBuilder` you need to not use *try/catch* block.
    final response = await http.get(`url?_offset=$offset&_limit=$limit`);
    final data = jsonDecode(response.data);
    
    return ListItems(data, reachedToEnd: data.length == 0);
  }
  
  @override
  bool shouldUpdate(MyListAdapter old) {
    return old.url != url;
  }
}

Getting Started

Add those lines to pubspec.yaml file and run flutter pub get.

dependencies:
  listview_utils: ">=0.2.2 <2.0.0"

Check out Installing tab for more details.

Import listview_utils package to your application by adding this line:

import 'package:listview_utils/listview_utils.dart';

This will import required classes to use listview_utils.

Properties

CustomListView( 
  // Items fetched per request (default: 30)
  pageSize: 30,

  // Header widget (default: null)
  header: Container(...),

  // Footer widget (default: null)
  footer: Container(...),

  // The widget that displayed if the list is empty (default: null)
  empty: Text('List is empty'),

  // Item provider adapter (default: null)
  adapter: ListAdapter(
    fetchItems: (int offset, int limit) {
      return ListItems([ ... ]);
    },
  ),
  
  //Pagination Mode [offset/page] (default: offset)
  paginationMode: PaginationMode.offset 
  
  //Initial offset (default: 0)
  initialOffset: 0
  


  // A callback function to build list items (required)
  itemBuilder: (BuildContext context, int index, dynamic item) {
    // If items provided by adapter the `item` argument will be matching element
    return ListTile(
      title: Text(item['title']),
    );
  },

  // Callback function to build widget if exception occurs during fetching items
  errorBuilder: (BuildContext context, LoadErrorDetails details, CustomListViewState state) {
    return Column(
      children: <Widget>[
        Text(details.error.toString()),
        RaisedButton(
          onPressed: () => state.loadMore(),
          child: Text('Retry'),
        ),
      ],
    );
  },

  // Item count
  itemCount: 45,

  // A callback function called when pull to refresh is triggered
  onRefresh: () async {
    ...
  },

  // Enable / disable pull to refresh (default: false)
  disableRefresh: false,
),

Adapters

ListView Utils currently only supports network adapter. Or you could write your own adapter by implementing BaseListAdapter mixin or using ListAdapter class.

Here's simple network adapter code using jsonplaceholder data.

NetworkListAdapter(
  url: 'https://jsonplaceholder.typicode.com/posts',
  limitParam: '_limit',
  offsetParam: '_start',
),

Controllers

Scroll controller

ListView Utils supports Flutter's built-in ScrollController, which allows for controlling the scrolling position:

class _SomeWidgetState extends State<SomeWidget> {
  ScrollController scrollController = ScrollController();

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        FlatButton(
          onPressed: () {
            scrollController.animateTo(100);
          },
          child: const Text('Scroll down'),
        ),
        Expanded(
          child: CustomListView(
            adapter: ...,
            scrollController: scrollController,
            itemBuilder: (context, index, dynamic item) {
              return ListTile(
                title: Text(item['title']),
              );
            },
          ),
        ),
      ],
    );
  }

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

List controller

ListView Utils also supports its own custom controller, which allows for controlling the list of items (for example, programmatically refreshing the list):

class _SomeWidgetState extends State<SomeWidget> {
  CustomListViewController listViewController = CustomListViewController();

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        FlatButton(
          onPressed: () {
            listViewController.refresh();
          },
          child: const Text('Refresh'),
        ),
        Expanded(
          child: CustomListView(
            adapter: ...,
            loadingBuilder: (context) => const Center(
              child: CircularProgressIndicator(),
            ),
            scrollController: scrollController,
            itemBuilder: (context, index, dynamic item) {
              return ListTile(
                title: Text(item['title']),
              );
            },
          ),
        ),
      ],
    );
  }

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