Let's say the ManageBookingPage widget requires an object called trip as an argument. But this widget has the ability to modify the received argument such that it becomes null (trip = null).

I want this widget to pop out of the tree automatically when trip becomes null. What would be the best approach in achieving this?

class ManageBookingPage extends StatefulWidget {
  const ManageBookingPage({
    super.key,
    required this.trip,
  });

  final BusTrip trip;

  @override
  State<ManageBookingPage> createState() => _ManageBookingPageState();
}

class _ManageBookingPageState extends State<ManageBookingPage> {
  @override
  Widget build(BuildContext context) {
    return SizedBox(
      child: Text(widget.trip.date.toString()),
    );
}

Solution

The solution I settled on:

• Make the parameter trip nullable.
• Add a null check in a conditional statement inside the build method and pop the widget out of tree if the argument becomes null.

class ManageBookingPage extends StatefulWidget {
  const ManageBookingPage({
    super.key,
    required this.trip,
  });

  final BusTrip? trip;

  @override
  State<ManageBookingPage> createState() => _ManageBookingPageState();
}

class _ManageBookingPageState extends State<ManageBookingPage> {
  @override
  Widget build(BuildContext context) {
    BusTrip? widgetTrip = widget.trip;

    if (widgetTrip != null) {
      String date = widget.trip.date.toString(); 
      return SizedBox(
       child: Text(date),
      );
    } else {
      return Builder(
        builder: (context) {
          Navigator.pop(context);
          return const SizedBox();
        },
      );
    }
  }
}