load more data in NestedScrollView with NotificationListener

NestedScrollViewLoadMore

import 'package:cartenz_djp/style/colors.dart';
import 'package:cartenz_djp/widget/override/customTabs.dart' as Tabs;
import 'package:flutter/material.dart';

class ExampleWidget extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => ExampleState();
}

class ExampleState extends State<ExampleWidget> {

  onLoadMore() {
    //Load More, do something
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: ColorWhite,
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: <Widget>[
          Expanded(
            child: Builder(builder: (BuildContext context) {
              return NestedScrollView(
                  //controller: scrollController,
                  headerSliverBuilder:
                      (BuildContext context, bool innerBoxIsScrolled) {
                return <Widget>[
                  SliverAppBar(
                    bottom: getTabHeader(),
                  )
                ];
              }, body: Builder(builder: (BuildContext context) {
                return Stack(children: <Widget>[
                  getTabBody(),
                ]);
              }));
            }),
          )
        ],
      ),
    );
  }

  Widget getTabHeader() {
    return Tabs.TabBar(tabs: [
      Tabs.Tab(child: Text("Tab 1")),
      Tabs.Tab(child: Text("Tab 2")),
      Tabs.Tab(child: Text("Tab 3")),
    ]);
  }

  Widget getTabBody() {
    return Column(
      children: <Widget>[
        Expanded(
            child: Tabs.TabBarView(children: [
          Container(
              child:

                  //Solved with this
                  NotificationListener<ScrollNotification>(
                        child: MediaQuery.removePadding(
                          context: context,
                          removeTop: true,
                          child: ListView.builder(
                              shrinkWrap: true,
                              itemCount: 3,
                              physics: NeverScrollableScrollPhysics(),
                              itemBuilder: (BuildContext context, int index) {
                                return Container();
                              })),
                        onNotification: (ScrollNotification scrollInfo) {
                          if (scrollInfo.metrics.pixels == scrollInfo.metrics.maxScrollExtent) {
                            //load more here
                            onLoadMore();
                          }
                          return false;
                        },
                      );

          Container(child: Container()),
          Container(child: Container())
        ]))
      ],
    );
  }
}

This does not trigger NestedScrollView. SliverAppbar does not get collapsed

yeah, with the new flutter version make the SliverAppBar do not get collapsed.

This does not trigger NestedScrollView. SliverAppbar does not get collapsed

In case someone stumbles upon this, you can wrap your inner ListView with a NotificationListener() and check if the Notification is an OverScrollNotification. This is how I got around the issue. As opposed to the solution described above (so no SingleChildScrollView and no Scrollcontroller inside your ListView)

I think, I tried this too, but not work. Maybe it runs correctly now.

btw, thanks for the answer

This does not trigger NestedScrollView. SliverAppbar does not get collapsed

In case someone stumbles upon this, you can wrap your inner ListView with a NotificationListener() and check if the Notification is an OverScrollNotification. This is how I got around the issue. As opposed to the solution described above (so no SingleChildScrollView and no Scrollcontroller inside your ListView)

I tried it, and it's work. thanks, dude

@IkhwanSI13 Please can you share your code i have the same issue.

   return Scaffold(
     appBar: AppBar(
       iconTheme: IconThemeData(
         color: Color(0xFF6991C7),
       ),
       title: Text(
         "Search",
         style: TextStyle(
             fontWeight: FontWeight.w700,
             fontSize: 18.0,
             color: Colors.black54,
             fontFamily: "Gotik"),
       ),
       centerTitle: true,
       backgroundColor: Colors.white,
       elevation: 0.0,
     ),
     body: SingleChildScrollView(
       primary: false,
       child: Container(
         color: Colors.white,
         padding: EdgeInsets.only(top: 15.0, bottom: 30.0),
         child:  Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: <Widget>[
             _textHello,
             BlocListener<FilterBloc, FilterState>(
               listener: (context, state) {
                 if (state is ErrorFilter) {
                   Scaffold.of(context).showSnackBar(
                     SnackBar(
                       content: Text(state.message),
                     ),
                   );
                 }
               },
               child: BlocBuilder<FilterBloc, FilterState>(
                 // ignore: missing_return
                 builder: (context, state) {
                   if (state is InitialFilter) {
                     return buildInitialInput();
                   } else if (state is LoadingFilter) {
                     return buildLoading();
                   } else if (state is LoadedFilter) {
                     if (state.products.isEmpty) {
                       return Column(
                         crossAxisAlignment: CrossAxisAlignment.center,
                         children: <Widget>[
                           ProductInputField(),
                           SizedBox(height: 30.0),
                           Center(child: Text('No content'))
                         ],
                       );
                     }
                     return Column(
                       children: <Widget>[
                         ProductInputField(),
                         SizedBox(height: 30.0),
                         NotificationListener<ScrollNotification>(
                           onNotification: (notification) => _onScrollNotification(notification, state),
                           child: GridView.builder(
                             physics: ScrollPhysics(),
                             itemCount: state.products.length,
                             primary: false,
                             shrinkWrap: true,
                             gridDelegate:
                             SliverGridDelegateWithFixedCrossAxisCount(
                               crossAxisSpacing: 10.0,
                               mainAxisSpacing: 10.0,
                               childAspectRatio: 0.605,
                               crossAxisCount: 2,
                             ),
                             itemBuilder: (context, pos) {
                               return ProductWidget(product: state.products[pos]);
                             },
                           ),
                         ),
                       ],
                     );
                   } else if (state is ErrorFilter) {
                     return buildInitialInput();
                   }
                 },
               ),
             ),
           ],
         )
       ),
     ),
   );
 }

 bool _onScrollNotification(ScrollNotification notif, LoadedFilter state) {
   if (notif is ScrollEndNotification && notif.metrics.pixels == notif.metrics.maxScrollExtent) {
     context.bloc<FilterBloc>().add(LoadMoreFilter(products: state.products, productName: 'a', stateName: ''));
   }
   return false;
 }

@IkhwanSI13 Please can you share your code i have the same issue.

   return Scaffold(
     appBar: AppBar(
       iconTheme: IconThemeData(
         color: Color(0xFF6991C7),
       ),
       title: Text(
         "Search",
         style: TextStyle(
             fontWeight: FontWeight.w700,
             fontSize: 18.0,
             color: Colors.black54,
             fontFamily: "Gotik"),
       ),
       centerTitle: true,
       backgroundColor: Colors.white,
       elevation: 0.0,
     ),
     body: SingleChildScrollView(
       primary: false,
       child: Container(
         color: Colors.white,
         padding: EdgeInsets.only(top: 15.0, bottom: 30.0),
         child:  Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: <Widget>[
             _textHello,
             BlocListener<FilterBloc, FilterState>(
               listener: (context, state) {
                 if (state is ErrorFilter) {
                   Scaffold.of(context).showSnackBar(
                     SnackBar(
                       content: Text(state.message),
                     ),
                   );
                 }
               },
               child: BlocBuilder<FilterBloc, FilterState>(
                 // ignore: missing_return
                 builder: (context, state) {
                   if (state is InitialFilter) {
                     return buildInitialInput();
                   } else if (state is LoadingFilter) {
                     return buildLoading();
                   } else if (state is LoadedFilter) {
                     if (state.products.isEmpty) {
                       return Column(
                         crossAxisAlignment: CrossAxisAlignment.center,
                         children: <Widget>[
                           ProductInputField(),
                           SizedBox(height: 30.0),
                           Center(child: Text('No content'))
                         ],
                       );
                     }
                     return Column(
                       children: <Widget>[
                         ProductInputField(),
                         SizedBox(height: 30.0),
                         NotificationListener<ScrollNotification>(
                           onNotification: (notification) => _onScrollNotification(notification, state),
                           child: GridView.builder(
                             physics: ScrollPhysics(),
                             itemCount: state.products.length,
                             primary: false,
                             shrinkWrap: true,
                             gridDelegate:
                             SliverGridDelegateWithFixedCrossAxisCount(
                               crossAxisSpacing: 10.0,
                               mainAxisSpacing: 10.0,
                               childAspectRatio: 0.605,
                               crossAxisCount: 2,
                             ),
                             itemBuilder: (context, pos) {
                               return ProductWidget(product: state.products[pos]);
                             },
                           ),
                         ),
                       ],
                     );
                   } else if (state is ErrorFilter) {
                     return buildInitialInput();
                   }
                 },
               ),
             ),
           ],
         )
       ),
     ),
   );
 }

 bool _onScrollNotification(ScrollNotification notif, LoadedFilter state) {
   if (notif is ScrollEndNotification && notif.metrics.pixels == notif.metrics.maxScrollExtent) {
     context.bloc<FilterBloc>().add(LoadMoreFilter(products: state.products, productName: 'a', stateName: ''));
   }
   return false;
 }

just check my code above. I updated it

@IkhwanSI13 Thanks for replying, Notifications Listener not working with multi ListView like my case, So i resolved this problem by add listener function instead of Notifications Listener.

Thanks for the code.It is working well 👍