Pass a function to the state of a stateless widget flutter

Question

I'm trying to do the exact same thing that poster in the following question about passing a function to the State of a a Stateful widget: Accessing a function of stateful widget in its state class? flutter

In this example (same one I'm working on and likely from the same youtube video), how do I move the function down to the stateful state section and passing the two parameters through the stateful constructor?

Would appreciate any help!

Why do you even what that? Just pass it to the StatefulWidget and call it from the state using `widget.myCallback(...)` — Günter Zöchbauer, Sep 26 '18 at 07:57
Does this answer your question? [Flutter - Passing Function to StatelessWidget not working](https://stackoverflow.com/questions/59668442/flutter-passing-function-to-statelesswidget-not-working) — Antonin GAVREL, Jan 13 '21 at 14:01
I flagged your question as "asked before", but it turns out that you were in fact the first to ask, although no one dared to write a detailed answer. ;) — Antonin GAVREL, Jan 13 '21 at 14:02

score 0 · Answer 1 · answered Apr 09 '22 at 02:16

You can pass the function callback to the StatelessWidget during initialization. That's my approach on initializing an ActionMenu that calls its functions from the parent class.

late ActionMenu actionMenu;

@override
void initState() {
  super.initState();
  // Initialize ActionMenu
  // arguments passed are Home Screen functions
  // that can be in ActionMenu class
  actionMenu = ActionMenu(this.settings, this.logout);
}

settings(){
  // TODO
}

logout(){
  // TODO
}

...and on the ActionMenu. You can now call the functions inside the StatelessWidget.

enum MenuOptions { menuSettings, menuLogout }

class ActionMenu extends StatelessWidget {
  final Function menuSettings, menuLogout;
  ActionMenu(this.menuSettings, this.menuLogout);

  @override
  Widget build(BuildContext context) {
    return PopupMenuButton<MenuOptions>(
      onSelected: (MenuOptions value) {
        switch (value) {
          case MenuOptions.menuSettings:
            this.menuSettings();
            break;
          case MenuOptions.menuLogout:
            this.menuLogout();
            break;
        }
      },
      itemBuilder: (BuildContext context) => <PopupMenuItem<MenuOptions>>[
        PopupMenuItem<MenuOptions>(
          value: MenuOptions.menuSettings,
          child: Text('Settings'),
        ),
        PopupMenuItem<MenuOptions>(
          value: MenuOptions.menuLogout,
          child: Text('Logout'),
        ),
      ],
    );
  }
}

Pass a function to the state of a stateless widget flutter

1 Answers1