list_view_with_data_source

A Flutter ListView in which list items, header, footer and separators build from section and item structured in DataSource.

About

This package abstracts the construction of elements to be displayed in a ListView, making it easier to manage. It's useful when arranging a variable number of multiple types of items. Also, by grouping elements with the concept of Sections, you can display different separators for each group and freely insert headers/footers.

It's inspired by UICollectionViewDataSource from UIKit.

The differences from grouped_list, which makes it easy to build groups from data, are as follows:

• By not automating group construction, it can express more complex switches
• Headers/footers/group separator Widgets can be set individually
• By separating the display structure and Widget construction, the structure itself can be verified

Example

This is an example of changing the items displayed based on the number of data entries per group.

The full text of this sample can be seen in example/lib/main/dart.

1. Add the package to your pubspec.yaml:

   list_view_with_data_source: ^1.0.0
   

2. define the Sections and Items to be stored in the DataSource. It's a good idea to match these with the types of Views.

class ProjectSection extends Equatable {
  const ProjectSection({
    required this.project,
    required this.itemCount,
  });

  final Project project;
  final int itemCount;

  ...
}

sealed class ProjectSectionItem {
  const ProjectSectionItem();
  String get title;
}

class TaskItem extends ProjectSectionItem {
  const TaskItem({
    required this.task,
  });

  final Task task;

  @override
  String get title => task.name;

  String get subtitle => task.type;
}

class EmptyItem extends ProjectSectionItem {
  const EmptyItem();

  @override
  String get title => 'No tasks';
}

2. Next, according to the data, fill the prepared Sections and Items into the ListViewDataSource.

final dataSource = CustomDataSource();
for (final project in projects) {
  final desktopTasks = project.tasks.whereType<DesktopTask>().toList();
  final section =
      ProjectSection(project: project, itemCount: desktopTasks.length);
  dataSource.addSection(section);
  if (desktopTasks.isNotEmpty) {
    dataSource.appendItems(
        section, desktopTasks.map((e) => TaskItem(task: e)).toList());
  } else {
    dataSource.appendItem(section, const EmptyItem());
  }
}

3. Place the ListViewWithDataSource Widget on the screen and start building the View.

ListViewWithDataSource(
  dataSource: _model.dataSourceFor(_filter),
  itemBuilder:
      (context, section, item, sectionIndex, itemIndex) =>
          switch (item) {
    (final TaskItem item) => ListTile(
        title: Text(item.title),
        subtitle: Text(item.subtitle),
        trailing:
            item.task.isComplete ? const Icon(Icons.check) : null,
      ),
    (final EmptyItem item) => ListTile(
        title: Text(item.title),
      ),
  },
  itemSeparatorBuilder:
      (context, section, item, sectionIndex, itemIndex,
              {required bool insideSection}) =>
          const Divider(indent: 16),
);