paginated_items_builder 1.0.4

Easier to display items in a list/grid view from your controllers directly or handling state internally with support for pagination.

PaginatedItemsBuilder For Flutter

Easier to display items in a list/grid view from your controllers directly or handling state internally with support for pagination. Saves the results in state to avoid unnecessary api calls everytime screen is pushed.

Screenshots

    

Usage

To use this plugin, add paginated_items_builder as a dependency in your pubspec.yaml file.

  dependencies:
    flutter:
      sdk: flutter
    paginated_items_builder:

First and foremost, import the widget.

import 'package:paginated_items_builder/paginated_items_builder.dart';

You can now add an PaginatedItemsBuilder widget to your widget tree.

Here, let's consider a list of products.

First, in the controller, let's define a variable for handling the products response. (typically inside the specific controller) and a public getter to access it in the UI.

PaginatedItemsResponse<Product>? _productsResponse;

PaginatedItemsResponse<Product>? get productsResponse => _productsResponse;

Now, define a function to handle the state of the list, function that handles calling the api and getting the results.

Future<void> updateProducts({
  bool reset = false,
  bool showLoaderOnReset = false,
}) async {
  if (reset && showLoaderOnReset) {
    _productsResponse = null;
    notifyListeners();
  }

  final res = await apiFunction(
    // startKey is optional and only required when you have pagination support in api
    startKey: reset ? null : _productsResponse?.paginationKey,
  );
  if (reset || _productsResponse == null) {
    _productsResponse = res;
  } else {
    _productsResponse!.update(res);
  }
  notifyListeners();
}

The apiFunction can be defined as:

Future<PaginatedItemsResponse<Product>?> apiFunction({
  // can be string or int (page number) or any other type.
  String? startKey,
}) async {
  // startKey necessary if pagination support
  final res = await _api.getProducts(startKey: startKey);

  return PaginatedItemsResponse<Product>(

    // list of items
    listItems: res.data?.products,

    // only required to pass if pagination supported, else null. (can be of any type)
    paginationKey: res.data?.paginationKey,

    // unique id, should only be passed in the repository function.
    // required for functions like `updateItem`, `findByUid`
    // and avoiding duplication of items in list (compares uid)
    idGetter: (product) => product.id,

  );
}

Now, can use this widget like shown in the widget tree: (No need to handle a refresh indicator separately. It is already present.)

When the reset from fetchPageData fn is true, your code should handle the logic to update and replace the existing contents. Basically update all items. Much like a pull-down refresh.

The same code is called when user pulls down to refresh on the view with reset: true to update all items.

PaginatedItemsBuilder<Product>(
    fetchPageData: (reset) => controller.updateProducts(
        reset: reset,
        showLoaderOnReset: reset,
    ),
    response: controller.productsResponse,
    itemBuilder: (context, index, item) => Text('Item$index : $item'),
),

Customization

To see the shimmer loader in play, you need to provide a mock items getter.. What basically happens is that this 'MockItem' is basically an object of the class T which is passed in the PaginatedItemsBuilder class.

Generate a class like shown:

class MockItems {
  static T? getByType<T>() {
    switch (T.toString()) {
      case 'Category':
        return _category as T;
    }
  }

  static final _category = Category.fromJson({
    'id': 'id',
    'name': '■■■■■■',
  });
}

and then pass the reference to the getByType function to the PaginatedItemsBuilderConfig.

PaginatedItemsBuilder.config = PaginatedItemsBuilderConfig(
    mockItemGetter: MockItems.getByType,
);

In the PaginatedItemsBuilderConfig, you can also customize the shimmer loader colors etc.

PaginatedItemsBuilder.config = PaginatedItemsBuilderConfig(
    mockItemGetter: MockItems.getByType,
    shimmerConfig: ShimmerConfig(
        baseColor: Colors.grey[300],
        highlightColor: Colors.grey[200],
    ),
);

The config can be initialized in the MaterialApp's builder property. It is also possible to pass different colors for different themes as shown:

MaterialApp(
    title: 'PaginatedItemsBuilder Demo',
    builder: (context, child) {
        late final Color shimmerBaseColor;
        late final Color shimmerHighlightColor;
        
        switch (Theme.of(context).brightness) {
            case Brightness.light:
                shimmerBaseColor = Colors.grey[300]!;
                shimmerHighlightColor = Colors.grey[100]!;
                break;
            case Brightness.dark:
                shimmerBaseColor = const Color(0xFF031956);
                shimmerHighlightColor = const Color(0x80031956);
                break;
        }
        
        PaginatedItemsBuilder.config = PaginatedItemsBuilderConfig(
            mockItemGetter: MockItems.getByType,
            shimmerConfig: ShimmerConfig(
                baseColor: shimmerBaseColor,
                highlightColor: shimmerHighlightColor,
                duration: const Duration(seconds: 1),
            ),
        );
        
        return child!;
    },
);

Want to show items as a grid? Change the cross axis count? Pass in a custom scroll controller? Well, there are a lot of parameters that can be customized in PaginatedItemsBuilder

See the example directory for a complete sample app.

Created & Maintained By Rithik Bhandari

• GitHub: @rithik-dev
• LinkedIn: @rithik-bhandari