[Bug] PageRequestListener gets triggered everytime i modify in itemList while a request is loading

[ibrahimEltayfe]

Steps to reproduce

1. Setup PagingController and add PageRequestListener callback

final MyPagingController<int, MyItem> pagingController =
      MyPagingController<int, MyItem>(firstPageKey: 1);
      
   pagingController.addPageRequestListener((pageKey) {
      print("NOTIFIED");
      //put your request here
    });

2. Add a delay before the request is triggered, simulating a scenario where the request doesn't execute immediately say 5 seconds.

3. After the initial page request is handled, scroll to the end of the list, triggering the next page request.

4. Modify the Item List while the second request is processing

  final List<MyItem> newList = List.from(pagingController?.itemList ?? []);
  
  // do your modification logic on newList for example, modify the isLiked variable in your list
  newList[index] = newList[index].copyWith(isLiked: !newList[index].isLiked);
  
  pagingController.itemList = newList;

4. While the next page request is still loading, make modifications to the itemList seems to cause the addPageRequestListener to be triggered again

Expected results

Modifying the itemList in the pagingController should not retrigger the addPageRequestListener if there is an active request or while the request is being processed.

Actual results

Modifying the itemList during an active request causes the addPageRequestListener to be triggered again unexpectedly.

Package Version

4.0.0

Platform

Android, iOS

Code sample

Code sample

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

  @override
  State<CodeSample> createState() => _CodeSampleState();
}

class _CodeSampleState extends State<CodeSample> {
  final PagingController<int, String> pagingController = PagingController(firstPageKey: 0);

  @override
  void initState() {
    pagingController.addPageRequestListener((pageKey) {
      print("NOTIFIED: $pageKey");
      Future.delayed(const Duration(seconds: 5), () {
        pagingController.appendPage(List.generate(20, (index) => "DUMMY ${index + (20 * pageKey)}"), pageKey + 1);
      },);
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PagedListView<int, String>(
          pagingController: pagingController,
          builderDelegate: PagedChildBuilderDelegate(
              itemBuilder: (BuildContext context, String item, int index) {
                return GestureDetector(
                  onTap: (){
                    List<String> newItems = List.from(pagingController.itemList ?? []);
      
                    int itemIndex = newItems.indexWhere((element) => element == item,);
      
                    if(itemIndex != -1){
                      newItems[itemIndex] = "MODIFIED $index";
                    }
      
                    pagingController.itemList = newItems;
                  },
                  child: Padding(
                    padding: const EdgeInsets.all(8),
                    child: Text(item, style: const TextStyle(fontSize: 18),),
                  ),
                );
              }
          )
      ),
    );
  }
}

Video

Screenshots / Video demonstration

Regular scenario

regular-scenario.mov

Issue

issue01.MOV

[yosifsamir]

we need a solution

[HasanShaddadKangaroo]

Again, we need a fix for this