Unable to use the .map function in Flutter - list

Question

So I am following along a book about Flutter App Development where I was tasked to implement a ToDoMenuItem class and create a list in it.
class TodoMenuItem {
final String title;
final Icon icon;
TodoMenuItem({this.title, this.icon});
List<TodoMenuItem> foodMenuList = [
TodoMenuItem(title: 'Fast Food', icon: Icon(Icons.fastfood)),
TodoMenuItem(title: 'Remind Me', icon: Icon(Icons.add_alarm)),
TodoMenuItem(title: 'Flight', icon: Icon(Icons.flight)),
TodoMenuItem(title: 'Music', icon: Icon(Icons.audiotrack)),
];
}
Then I was tasked to map it to a PopUpMenuButtonWidget using an itemBuilder. Here is the class I wrote for it.
class PopupMenuButtonWidget extends StatelessWidget
implements PreferredSizeWidget {
const PopupMenuButtonWidget({
Key key,
}) : super(key: key);
#override
Widget build(BuildContext context) {
return Container(
color: Colors.lightGreen.shade100,
height: preferredSize.height,
width: double.infinity,
child: Center(
child: PopupMenuButton<TodoMenuItem>(
icon: Icon(Icons.view_list),
onSelected: ((valueSelected) {
print('valueSelected: ${valueSelected.title}');
}),
itemBuilder: (BuildContext context) {
return foodMenuList.map((TodoMenuItem todoMenuItem) {
return PopupMenuItem<TodoMenuItem>(
value: todoMenuItem,
child: Row(
children: <Widget>[
Icon(todoMenuItem.icon.icon),
Padding(
padding: EdgeInsets.all(8.0),
),
Text(todoMenuItem.title),
],
),
);
}).toList();
},
),
),
);
}
#override // implement preferredSize
Size get preferredSize => Size.fromHeight(75.0);
}
However, it returns an error at this line.
return foodMenuList.map((TodoMenuItem todoMenuItem) {
And the error says
Undefined name 'foodMenuList'.
Try correcting the name to one that is defined, or defining the name.
How can I 'map' the foodMenuList list to the widget?

Answer 1

Your foodMenuList is declared in todoMenuItem class, while you try to refer to it like it would be a part of PopupMenuButtonWidget (you are doing this.foodMenuList in context of PopupMenuButtonModget)
You could create instantiate an instance of TodoMenuList in PopupMenuButtonWidget and then use it.
final TodoMenuItem _todoMenu = TodoMenuItem();
Widget build(BuildContext context) {
...
// Someplace where you need to use the list
_todoMenu.foodMenuList
...
}