DatePicker

sample.packages.flutter.lib.src.material.date_picker.119.

This sample demonstrates how to create a restorable Material date picker. This is accomplished by enabling state restoration by specifying [MaterialApp.restorationScopeId] and using [Navigator.restorablePush] to push [DatePickerDialog] when the button is tapped.

  
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      restorationScopeId: 'app',
      title: _title,
      home: MyStatefulWidget(restorationId: 'main'),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key, this.restorationId}) : super(key: key);

  final String? restorationId;

  @override
  State createState() => _MyStatefulWidgetState();
}

/// RestorationProperty objects can be used because of RestorationMixin.
class _MyStatefulWidgetState extends State
    with RestorationMixin {
  // In this example, the restoration ID for the mixin is passed in through
  // the [StatefulWidget]'s constructor.
  @override
  String? get restorationId => widget.restorationId;

  final RestorableDateTime _selectedDate =
      RestorableDateTime(DateTime(2021, 7, 25));
  late final RestorableRouteFuture _restorableDatePickerRouteFuture =
      RestorableRouteFuture(
    onComplete: _selectDate,
    onPresent: (NavigatorState navigator, Object? arguments) {
      return navigator.restorablePush(
        _datePickerRoute,
        arguments: _selectedDate.value.millisecondsSinceEpoch,
      );
    },
  );

  static Route _datePickerRoute(
    BuildContext context,
    Object? arguments,
  ) {
    return DialogRoute(
      context: context,
      builder: (BuildContext context) {
        return DatePickerDialog(
          restorationId: 'date_picker_dialog',
          initialEntryMode: DatePickerEntryMode.calendarOnly,
          initialDate: DateTime.fromMillisecondsSinceEpoch(arguments! as int),
          firstDate: DateTime(2021),
          lastDate: DateTime(2022),
        );
      },
    );
  }

  @override
  void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
    registerForRestoration(_selectedDate, 'selected_date');
    registerForRestoration(
        _restorableDatePickerRouteFuture, 'date_picker_route_future');
  }

  void _selectDate(DateTime? newSelectedDate) {
    if (newSelectedDate != null) {
      setState(() {
        _selectedDate.value = newSelectedDate;
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
          content: Text(
              'Selected: ${_selectedDate.value.day}/${_selectedDate.value.month}/${_selectedDate.value.year}'),
        ));
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: OutlinedButton(
          onPressed: () {
            _restorableDatePickerRouteFuture.present();
          },
          child: const Text('Open Date Picker'),
        ),
      ),
    );
  }
}