Flutter for Beginners

Turn the widget into a FormField widget

To turn the widget into a FormField widget, we start by creating a widget that extends the FormField class, which is a StatefulWidget with some Form facilities.

This time, let's start by checking out the new widget's associated State object. Let's do it by breaking it into parts:

// initial part of _VerificationCodeFormFieldState  final TextEditingController _controller = TextEditingController(text: ""); @override void initState() {   super.initState();   _controller.addListener(_controllerChanged); }

From the preceding code, you can check it has a single _controller field, which represents the controller used by the FormField widget. It must be in the State so it persists against layout changes. As you ...