Scrollable Listview in Flutter with Dart

Question

Can someone explain me where I should define a scroll controller? I have chat list view which is the body of a scrollable view. I want to be able to control the scrolling behaviour from MainView but don't know how to pass the controller down to _ChatListView. Any ideas?

mainview.dart

class MainView extends StatelessWidget {
    ...
    // is this the correct place?
    final ScrollController scrollController = ScrollController();

    @override
    Widget build(BuildContext context) {
        return new Scaffold(
            body: new ChatListView()
        );
    }
}

chatlistview.dart

class ChatListView extends StatefulWidget {
    @override
    _ChatListView createState() => _ChatListView();
}

class _ChatListView extends State< ChatListView > {
    Widget build(BuildContext context) {
        return ListView.builder(
          controller: scrollController,
          );
    }
}

Solution

Add a constructor and pass the controller as parameter

class MainView extends StatelessWidget {
    ...
    // is this the correct place?
    final ScrollController scrollController = ScrollController();

    @override
    Widget build(BuildContext context) {
        return new Scaffold(
            body: new ChatListView(scrollController: scrollController)
        );
    }
}

class ChatListView extends StatefulWidget {
    ChatListView({@required this.scrollController}); 

    final ScrollController scrollController;

    @override
    _ChatListView createState() => _ChatListView();
}

class _ChatListView extends State< ChatListView > {

    Widget build(BuildContext context) {
        return ListView.builder(
          controller: widget.scrollController,
          );
    }
}

Comments

[Daniel Stephens]

Perfect, the widget object was finally what I was looking for! Thanks