I have my app connected to graphql using ferry and pagination working. Right now it fetches the first 25 results when the page loads and then when I scroll to the bottom it fetches the next 25. Below is the code that does that.

final getAllPartnerOrganizationsReq = GGetAllPartnerOrganizationsReq(
    (b) => b
      ..requestId = 'MyReviewsReq'
      ..vars.offset = 0
      ..vars.limit = 25,
  );

  void getNextPartnerOrganizations(int offset, int limit) {
    final nextGetAllPartnerOrganizationsReq =
        getAllPartnerOrganizationsReq.rebuild((b) => b
          ..requestId = 'MyReviewsReq'
          ..vars.offset = offset
          ..vars.limit = limit
          ..updateResult = (previous, result) {
            if (previous == null) {
              return result;
            }
            return previous.rebuild((b) => b
              ..partnerOrganizations
                  .addAll(result!.partnerOrganizations!.asList()));
          });
    client.requestController.add(nextGetAllPartnerOrganizationsReq);
  }

  @override
  void initState() {
    super.initState();
    client.request(getAllPartnerOrganizationsReq).listen((response) {
      for (var i = offset;
          i < response.data!.partnerOrganizations!.length;
          i  ) {
        partners.add(response.data!.partnerOrganizations![i]);
      }
      offset  = 25;
      setState(() {});
    });

    _scrollController.addListener(() {
      if (_scrollController.position.pixels ==
          _scrollController.position.maxScrollExtent) {
        getNextPartnerOrganizations(offset, 25);
      }
    });
  }

THE QUESTION: I want to have a function that resets this list view completely. I have two needs, one will be a simple refresh icon that resets the list back to the initial 25 and the other will be as part of a search, so if the user searches using a term it removes the list and refetches using those terms. I dont need to know how to use search, I basically need a way to just remove everything from the ListView and get back to a blank slate. Below is the the code relating to where the ListView lives.

@override
  Widget build(BuildContext context) {
    final model = Provider.of<RetailerDetailsModel>(context, listen: false);

    return Scaffold(
      appBar: AppBar(
        title: const Text('Data Management System'),
      ),
      body: LayoutBuilder(
        builder: (context, constraints) {
          if (partners.isNotEmpty) {
            print('partners');
            return ListView.separated(
              controller: _scrollController,
              itemBuilder: (context, index) => Card(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: <Widget>[
                    ListTile(
                      leading: kIsWeb
                          ? FadeInImage.assetNetwork(
                              width: 100,
                              height: double.infinity,
                              imageErrorBuilder: (context, index, error) =>
                                  const Text('Failed to load'),
                              image: 'https://${partners[index].logo}',
                              placeholder: 'assets/logo.jpg',
                            )
                          : CachedNetworkImage(
                              imageUrl: 'https://${partners[index].logo}',
                              placeholder: (context, url) =>
                                  const CircularProgressIndicator(),
                              fit: BoxFit.contain,
                              width: 100,
                              height: double.infinity,
                            ),
                      title: Text(partners[index].companyName),
                      subtitle: Text(
                        partners[index].ogDescription ?? 'No Description Set',
                        maxLines: 3,
                      ),
                      trailing:
                          Text(partners[index].ecommTechnology ?? 'Unknown'),
                    ),

CodePudding user response：

Since the definition of the partners variable isn't provided in the code, this answer assumes that it is some kind of a list by looking at how it's used in the code.

To remove all entries in the ListView, you can just reset this list.

setState((){
 partners = [];
})