There's an issue with fetching data for the next page.

[Patrick386]

I've written a small sample code for testing as follows. The issue is that it's not fetching the next page. Can you help identify and fix any problems in the code?

class DemoView extends StatefulWidget {
  const DemoView({super.key});

  @override
  State<DemoView> createState() => _DemoViewState();
}

class _DemoViewState extends State<DemoView> {
  final PagingController<int, DemoData> _pagingController =
      PagingController<int, DemoData>(firstPageKey: 0);

  late HitsSearcher _hitsSearcher;
  Stream<_HitsPage> get _searchPage =>
      _hitsSearcher.responses.map(_HitsPage.fromResponse);

  @override
  void initState() {
    _hitsSearcher = HitsSearcher(
      applicationID: Env.algoliaApplicationID,
      apiKey: Env.algoliaApiKey, // adminKey search-only demo key
      indexName: AlgoliaCredentials.demoEcommerceIndex, // demo_ecommerce
    );

    _searchPage.listen((_HitsPage page) {
      if (page.pageKey == 0) {
        _pagingController.refresh();
      }
      logger.info('nextPageKey:${page.nextPageKey} / Page item length:${page.items.length}'); // 1 / 20
      _pagingController.appendPage(page.items, page.nextPageKey);
    }).onError((error) => _pagingController.error = error);

    _pagingController.addStatusListener((status) {
      // status:PagingStatus.ongoing
      logger.info('status:${status.toString()}');
    });
    super.initState();
  }
  @override
  void dispose() {
    _pagingController.dispose();
    _hitsSearcher.dispose();
    super.dispose();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
     appBar: AppBar(),

      body: PagedListView<int, DemoData>(
          pagingController: _pagingController,
          builderDelegate: PagedChildBuilderDelegate<DemoData>(
              noItemsFoundIndicatorBuilder: (_) => const Center(
                    child: Text('No results found')),
              itemBuilder: (_, DemoData item, __) => Container(
                    color: Colors.white,
                    height: 80,
                    padding: const EdgeInsets.all(8),
                    child: Row(
                      children: [
                        if (item.image != null)
                          SizedBox(
                              width: 50, child: Image.network(item.image!)),
                        const SizedBox(width: 20),
                        Expanded(child: Text('${item.name}'))
                      ],
                    ),
                  ))),
    );

  }
}

class _HitsPage {
  const _HitsPage(this.items, this.pageKey, this.nextPageKey);

  final List<DemoData> items;
  final int pageKey;
  final int? nextPageKey;

  factory _HitsPage.fromResponse(SearchResponse response) {
    final items = response.hits.map(DemoData.fromJson).toList();
    final isLastPage = response.page >= response.nbPages;
    final nextPageKey = isLastPage ? null : response.page + 1;

    //INFO: Algolia page: 0, nbPages: 50, isLastPage: false, nextPageKey: 1
    logger.info('Algolia page: ${response.page}, nbPages: ${response.nbPages}, isLastPage: $isLastPage, nextPageKey: $nextPageKey');

    return _HitsPage(items, response.page, nextPageKey);
  }
}

https://github.com/algolia/algoliasearch-helper-flutter/assets/49754877/12742152-2b9c-44ae-a209-230497cf859f

[Patrick386]

I accidentally omitted the listener that passes the incremented page key to the page controller. Issue resolved.

[reemora]

لقد كتبت نموذجًا صغيرًا من التعليمات البرمجية للاختبار على النحو التالي. المشكلة هي أنها لا تجلب الصفحة التالية. هل يمكنك المساعدة في تحديد وإصلاح أي مشاكل في الكود؟

class DemoView extends StatefulWidget {
  const DemoView({super.key});

  @override
  State<DemoView> createState() => _DemoViewState();
}

class _DemoViewState extends State<DemoView> {
  final PagingController<int, DemoData> _pagingController =
      PagingController<int, DemoData>(firstPageKey: 0);

  late HitsSearcher _hitsSearcher;
  Stream<_HitsPage> get _searchPage =>
      _hitsSearcher.responses.map(_HitsPage.fromResponse);

  @override
  void initState() {
    _hitsSearcher = HitsSearcher(
      applicationID: Env.algoliaApplicationID,
      apiKey: Env.algoliaApiKey, // adminKey search-only demo key
      indexName: AlgoliaCredentials.demoEcommerceIndex, // demo_ecommerce
    );

    _searchPage.listen((_HitsPage page) {
      if (page.pageKey == 0) {
        _pagingController.refresh();
      }
      logger.info('nextPageKey:${page.nextPageKey} / Page item length:${page.items.length}'); // 1 / 20
      _pagingController.appendPage(page.items, page.nextPageKey);
    }).onError((error) => _pagingController.error = error);

    _pagingController.addStatusListener((status) {
      // status:PagingStatus.ongoing
      logger.info('status:${status.toString()}');
    });
    super.initState();
  }
  @override
  void dispose() {
    _pagingController.dispose();
    _hitsSearcher.dispose();
    super.dispose();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
     appBar: AppBar(),

      body: PagedListView<int, DemoData>(
          pagingController: _pagingController,
          builderDelegate: PagedChildBuilderDelegate<DemoData>(
              noItemsFoundIndicatorBuilder: (_) => const Center(
                    child: Text('No results found')),
              itemBuilder: (_, DemoData item, __) => Container(
                    color: Colors.white,
                    height: 80,
                    padding: const EdgeInsets.all(8),
                    child: Row(
                      children: [
                        if (item.image != null)
                          SizedBox(
                              width: 50, child: Image.network(item.image!)),
                        const SizedBox(width: 20),
                        Expanded(child: Text('${item.name}'))
                      ],
                    ),
                  ))),
    );

  }
}

class _HitsPage {
  const _HitsPage(this.items, this.pageKey, this.nextPageKey);

  final List<DemoData> items;
  final int pageKey;
  final int? nextPageKey;

  factory _HitsPage.fromResponse(SearchResponse response) {
    final items = response.hits.map(DemoData.fromJson).toList();
    final isLastPage = response.page >= response.nbPages;
    final nextPageKey = isLastPage ? null : response.page + 1;

    //INFO: Algolia page: 0, nbPages: 50, isLastPage: false, nextPageKey: 1
    logger.info('Algolia page: ${response.page}, nbPages: ${response.nbPages}, isLastPage: $isLastPage, nextPageKey: $nextPageKey');

    return _HitsPage(items, response.page, nextPageKey);
  }
}

شاشة.تسجيل.2023-11-26.at.4.35.28.PM.mov