Riverpod notifier provider call function

I have been using provider as state management and had newly migrated to riverpod. Riverpod has a lot of providers which is confusing for me. I am using NotifierProvider and have issue calling a function

Here is the screen and the function. I wanted to access the update function but i can only access the model variables. Error says “The getter ‘notifier’ isn’t defined for the type ‘SignupModel'”

    class SignUpScreen extends ConsumerStatefulWidget {
  static const routeName = Screens.signUpScreen;

  @override
  ConsumerState<SignUpScreen> createState() => _SignUpScreenState();
}

class _SignUpScreenState extends ConsumerState<SignUpScreen> {


 onSubmit() async {
    LoggerService.log(LogEventType.ButtonPress,
        LogDetails(buttonName: 'onSubmit', displayName: 'Sign Up Screen'));
    final registerChangeNotifier =ref.watch(registerChangeNotifierProvider);
    //can't call update function
    ref.read(registerChangeNotifier.notifier).update()
  
    try {
      if (_formKey.currentState!.validate() && isChecked) {
        //Close keyboard
        Navigator.of(context, rootNavigator: true)
            .pushNamed(EmailOtpScreen.routeName);
      }
    } catch (e, stackTrace) {
      LoggerService.log(
          LogEventType.Warning,
          LogDetails(
              error: e,
              message: e?.toString() ?? e?.toString(),
              stackTrace: stackTrace));
    }
  }

here is the provider

class RegisterProvider extends Notifier<SignupModel> {

  @override
  SignupModel build() {
    return SignupModel(email: '');
  }

  void update() {
  }

}

From the documentation:

ref.watch is used inside the build method of a widget or inside the body of a provider to have the widget/provider listen to a provider

If you want to call the update method from your Notifier, use the same way as the docs demonstrated how to call the increment method here.

That is, in your case, the way to call it is:

ref.read(registerChangeNotifierProvider.notifier).update();

and remove the ref.watch line.

I suggest you to familiarize yourself with the use of ref.watch, ref.read, ref.listen, notifiers and providers from the documentation in general.