Whenever I "long flick" the year-wheel of the Cupertino date picker (in my Android app), such that the min or max year is crossed by the wheel, an exception arises with the following message:

Exception has occurred.
_AssertionError ('package:flutter/src/cupertino/date_picker.dart': Failed assertion: line 327 pos 10: '(mode != CupertinoDatePickerMode.date && mode != CupertinoDatePickerMode.monthYear) ||
             (minimumYear >= 1 && (initialDateTime ?? DateTime.now()).year >= minimumYear)': initial year is not greater than minimum year, or minimum year is not positive)

I have properly set the initialDateTime to DateTime.now() and minimumYear to 2000 and maximumYear to 2050. Despite this the exception arises and I don't know why. How can I solve this exception during such flicks of the year wheel?

Full code:

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: const MyHomePage());
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  DateTime _dateTime = DateTime.now();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).primaryColor,
        title: const Text("Inbuild Cupertino Date Picker Example"),
      ),
      body: Column(
        children: [
          Flexible(
            child: CupertinoDatePicker(
              initialDateTime: _dateTime,
              dateOrder: DatePickerDateOrder.ymd,
              mode: CupertinoDatePickerMode.date,
              minimumYear: 2000,
              maximumYear: 2050,
              onDateTimeChanged: (newDateTime) {
                print("############## DateTime: ${newDateTime}");
                setState(() {
                  _dateTime = newDateTime;
                });
              },
            ),
          ),
        ],
      ),
      bottomNavigationBar: Container(
        padding: EdgeInsets.all(15.0),
        height: 60.0,
        width: double.infinity,
        decoration: BoxDecoration(color: Colors.amberAccent),
        child: const Text("Bottom Navigation Bar"),
      ),
    );
  }
}

Whenever I "long flick" the year-wheel of the Cupertino date picker (in my Android app), such that the min or max year is crossed by the wheel, an exception arises with the following message:

Exception has occurred.
_AssertionError ('package:flutter/src/cupertino/date_picker.dart': Failed assertion: line 327 pos 10: '(mode != CupertinoDatePickerMode.date && mode != CupertinoDatePickerMode.monthYear) ||
             (minimumYear >= 1 && (initialDateTime ?? DateTime.now()).year >= minimumYear)': initial year is not greater than minimum year, or minimum year is not positive)

I have properly set the initialDateTime to DateTime.now() and minimumYear to 2000 and maximumYear to 2050. Despite this the exception arises and I don't know why. How can I solve this exception during such flicks of the year wheel?

Full code:

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: const MyHomePage());
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  DateTime _dateTime = DateTime.now();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).primaryColor,
        title: const Text("Inbuild Cupertino Date Picker Example"),
      ),
      body: Column(
        children: [
          Flexible(
            child: CupertinoDatePicker(
              initialDateTime: _dateTime,
              dateOrder: DatePickerDateOrder.ymd,
              mode: CupertinoDatePickerMode.date,
              minimumYear: 2000,
              maximumYear: 2050,
              onDateTimeChanged: (newDateTime) {
                print("############## DateTime: ${newDateTime}");
                setState(() {
                  _dateTime = newDateTime;
                });
              },
            ),
          ),
        ],
      ),
      bottomNavigationBar: Container(
        padding: EdgeInsets.all(15.0),
        height: 60.0,
        width: double.infinity,
        decoration: BoxDecoration(color: Colors.amberAccent),
        child: const Text("Bottom Navigation Bar"),
      ),
    );
  }
}

• flutter
• exception
• flutter-cupertino
• cupertino-widgets

1 Answer 1

You don't need to update initialDateTime every setState. Introduce a new variable for selected date. Initially both of them will be same when you change to another date then:

_dateTime <-- DateTime.now()
_selectedDateTime <-- Next Selected date in CupertinoDatePicker

Following are changes required in your code:

final DateTime _dateTime = DateTime.now();
DateTime _selectedDateTime = DateTime.now();

      Flexible(
        child: CupertinoDatePicker(
          initialDateTime: _dateTime,
          dateOrder: DatePickerDateOrder.ymd,
          mode: CupertinoDatePickerMode.date,
          minimumYear: 2000,
          maximumYear: 2050,
          onDateTimeChanged: (newDateTime) {
            print("############## DateTime: ${newDateTime}");
            setState(() {
              //CHANGED THIS VARIABLE
              _selectedDateTime = newDateTime;
            });
          },
        ),

I tested it on my device and there are no exceptions. If the issue still exists on your side, please mention you flutter and dart versions