DateTime Helpers

Dependencies
dart:math and package:intl/intl.dart

This file contains all the common Date and Time helpers which can be used in the app.

Extension On TimeOfDay

Get TimeOfDay in HH:MM AM/PM format. DateTime extension contains toHMaa getter on the extension so it translates DateTime to HH:MM AM/PM.

final TimeOfDay time = TimeOfDay.now();
print(time.toHMaa);

String formatExt({String format = 'hh:mm a'}) =>
    DateFormat(format).format(DateTime(0, 0, 0, hour, minute));

Extension On DateTime

Note:
In database developer should save DateTime in UTC if possible. And Developer will have to be carefull when working with Timezone.

We have offset with respect to UTC time so we can change timezone with respect to UTC only. We will walk you through few use cases and how they should be handled.

Example of valid Timezones: Asia/Kolkata, ASIA/KOLKATA, asia/kolkata, Also check list of available timezones here

Usecase: We receive UTC time from database and we want to change it for specific timezone.

DateTime? date = DateTimeHelper.toTimezone('Asia/Kolkata', dateString);

Usecase: We have DateTime for specific timezone and we want to change it to UTC.

let's assume we have two properties in our model, one datekey and other timezonekey. And for some reason when we use date we don't want to use it as UTC.

DateTime? date = DateTimeHelper.fromTimezone(timezonekey, datekey);

Usecase: We have to change DateTime from one timezone (known priorly) to another timezone.

Let's say I have my DateTime according to ABC timezone and I want to change it to LMN timezone then First I'll have to convert ABC to UTC and then we can convert that UTC to LMN. But why do we have to go back to UTC when we want to change from one timezone to another timezone? Because we have time offsets respected to UTC.

let's assume we have two properties in our model, one datekey and other timezonekey. And newtimezone holds new timezone value.

DateTime? date = DateTimeHelper.fromTimezone(timezonekey, datekey)?.toTimezone(newtimezone);

Usecase: We have to change DateTime from one timezone (not known priorly) to another timezone.

for reference in below explaination:

Region	DateTime
EST	2023-01-01 00:00:00 am
IST	2023-01-01 10:30:00 am

Now why can't we convert DateTime from one timezone (not known priorly) to another timezone. e.g. let's try to convert EST (unknown) DateTime to IST DateTime. Date property from database looks something like: 2023-01-01 00:00:00 now we parse it in flutter, flutter gives us DateTime object as local. If I live in India it will give me DateTime object with same properties of 2023-01-01 00:00:00 and not with properties of 2023-01-01 10:30:00. Which is not correct. You can try everything/ available extension methods but you won't get correct results to show if you don't know the timezone.

Note:
When we change timezone the DateTime, it will be converted to UTC. In Flutter we don't have setter for timeZoneName property on DateTime, so we don't know from which timzeone DateTime has and if we don't know that we can't convert that time to UTC automatically in our extension, because for every timezone offsets are different, And as we have said We can change timezone with respect to UTC. That's why if you want to remeber timezone, you have to maintain a separate property.

DateTimeHelper

fromTimezone method: This method from DateTimeHelper class returns UTC datetime. `timezone` and `datetime` parameters are mendatory to pass, you can pass daylight true if the `datetime` is calculated depending on daylight, you can pass custom `pattern` if you're saving datetime in custom format.

static DateTime? fromTimezone(
  String timezone,
  String datetime, {
  String pattern = 'yyyy-MM-dd hh:mm:ss',
  bool daylight = false,
}) {
  // Will return UTC DateTime
  return DateFormat(pattern).parse(datetime, true).fromTimezone(timezone, daylight: daylight);
}

// Call
DateTime? datetime = DateTimeHelper.fromTimezone(
  'utc',
  '2023-01-01',
  pattern: 'yyyy-MM-dd',
);

toTimezone method: this method will give desired timezone datetime from UTC. You can pass daylight true if you want the results depending on daylight, you can pass custom `pattern` if you're saving datetime in custom format.

static DateTime? toTimezone(
  String timezone,
  String datetime, {
  String pattern = 'yyyy-MM-dd hh:mm:ss',
  bool daylight = false,
}) {
  return DateFormat(pattern).parse(datetime, true).toTimezone(timezone, daylight: daylight);
}

DateTime? datetime = DateTimeHelper.toTimezone(
  'Asia/Kolkata',
  '2023-01-01 10:30:00.000Z',
  pattern: 'yyyy-MM-dd hh:mm:ss.000Z',
);

Other DateTime Extensions

Get DateTime with zero milliseconds and microsecond

final DateTime date = DateTime.now();
print(date.resetMillisecond);

Get DateTime for n days before provided DateTime

final DateTime date = DateTime.now();
print(date.daysBefore(2));

Get DateTime for n days after provided DateTime

final DateTime date = DateTime.now();
print(date.daysAfter(2));

Get DateTime for the next day start

final DateTime date = DateTime.now();
print(date.nextDayStart);

returns xxxx-xx-xx 00:00:00.000

Get Date only (time is set to zero) (if DateTime type is UTC then return UTC otherwise return local)

final DateTime date = DateTime.now();
print(date.onlyDate);

returns year, month, date

Get Month only (time is set to zero and date is set to first) (if DateTime type is UTC then return UTC otherwise return local)

final DateTime date = DateTime.now();
print(date.onlyMonth);

returns xxxx-xx-01 00:00:00.000

Get Time only

final DateTime date = DateTime.now();
print(date.onlytime(01, 15));

can pass optional arguments hours and minutes, the first argument will be hour always. returns (epoch date + time) 1970-01-01 xx:xx:00.000z

Get UTC Time First Day Since Epoch

final DateTime date = DateTime.now();
print(date.utcTimeFirstDaySinceEpoch);

returns (epoch date + time with milli and micro secs) 1970-01-01 xx:xx:xx.xxxz

Get UTC DateTime

final DateTime date = DateTime.now();
print(date.asUtc);

Get Local DateTime

final DateTime date = DateTime.now();
print(date.asLocal);

Get Client DateTime

final DateTime date = DateTime.now();
print(date.asClient);

Get MMM DD HH:MM AM/PM formatted string

final DateTime date = DateTime.now();
print(date.toDateTimeString);

Get EEEE Month DD HH:MM AM/PM formatted string

final DateTime date = DateTime.now();
print(date.toFullDateTimeString);

Get EEE Month DD formated string

final DateTime date = DateTime.now();
print(date.toFullDateString);

Get HH:MM AM/PM formatted string

final DateTime date = DateTime.now();
print(date.toHMaa);

Get HH:MM:SS AM/PM formatted string

final DateTime date = DateTime.now();
print(date.toHHMMSS);

Get Month(short) Date formated string

final DateTime date = DateTime.now();
print(date.toMMMMdd);

Get Year-Month(short)-Date formated string

final DateTime date = DateTime.now();
print(date.toYyyymmmdd);

Get Date of Birth (YYYY-MM-DD) formatted string

final DateTime date = DateTime.now();
print(date.toDateOfBirth);

Get Custom formatted string

by default format will be : 'yyyy MMM dd, h:mm a'

mm will be used for Minutes and MM, MMM, MMMM will be used for Month.

DateTime date = DateTime.now();
Log.info(date.format(format: 'yyyy-MM-dd'), disableCloudLogging: true);

Extension On String

From String to DateTime

final DateTime date = '2023-01-01 00:00:00'.toDateTime();

you can pass a valid pattern in toDateTime function to convert the string from that format, default pattern is 'yyyy-mm-dd hh:mm:ss'

Add zeros as a prefix to equalize the length

const String number = '100';
print(number.zeroPrefix(6));

Parse string to int and double

const String number = '100';
final int? numInt = number.parseInt;
final double? numDouble = number.parseDouble;

Extension on Duration

Get formatted String

const Duration dur = Duration(days:3, hours: 20, minutes: 10);
print(dur.format);

will give output HH:MM:SS

Get HH:MM:SS formatted String

const Duration dur = Duration(days:3, hours: 20, minutes: 10);
print(dur.toHms);

will give output HH:MM:SS (Two Digit Hours, Two Digit Minutes, Two Digit Seconds)

Get MM:SS formatted String

const Duration dur = Duration(days:3, hours: 20, minutes: 10);
print(dur.toMs);

will give output MM:SS (Two Digit Minutes, Two Digit Seconds)

Extension on int

Get Local and UTC time from Milliseconds Since Epoch

final int millisecondsSinceEpoch = DateTime.now().millisecondsSinceEpoch;
print(millisecondsSinceEpoch.localDateTime);
print(millisecondsSinceEpoch.utcDateTime);

Get DateTime from Milliseconds Since Epoch

final int millisecondsSinceEpoch = DateTime.now().millisecondsSinceEpoch;
final DateTime date = millisecondsSinceEpoch.asDateTime(from: TimeZone.local);

The argument is optional.

Get DateTime from Milliseconds Since Epoch

final int millisecondsSinceEpoch = DateTime.now().millisecondsSinceEpoch;
final DateTime date = millisecondsSinceEpoch.asDateTime(from: TimeZone.local);

The from argument is optional.

Source code for datetime.dart

import 'dart:math';

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

enum TimeZone { utc, local }

extension TimeOfDayExtension on TimeOfDay {
  // HH:MM AM
  String get toHMaa => DateFormat('hh:mm aaaa').format(DateTime(0, 0, 0, hour, minute));
}

// Extension for DateTime
extension DateTimeExtension on DateTime {
  String toTime(BuildContext context) => TimeOfDay.fromDateTime(asLocal).format(context);

  // Return DateTime with zero millisecond and microsecond
  DateTime get resetMillisecond => DateTime(year, month, day, hour, minute, second);

  DateTime daysBefore(int days) => subtract(Duration(days: days));

  DateTime daysAfter(int days) => add(Duration(days: days));

  DateTime get nextDayStart => onlyDate.daysAfter(1);

  DateTime get localTimeToday {
    DateTime now = DateTime.now();
    return DateTime(
      now.year,
      now.month,
      now.day,
      hour,
      minute,
      second,
      millisecond,
      microsecond,
    );
  }

  DateTime get onlyDate => isUtc ? DateTime.utc(year, month, day) : DateTime(year, month, day);

  DateTime get onlyMonth => isUtc ? DateTime.utc(year, month) : DateTime(year, month);

  DateTime onlyTime([int? hourArg, int? minuteArg]) =>
      DateTime.utc(1970, 1, 1, hourArg ?? hour, minuteArg ?? minute, 0, 0, 0);

  DateTime get utcTimeFirstDaySinceEpoch =>
      DateTime.utc(1970, 1, 1, hour, minute, second, millisecond, microsecond);

  // Convert local time as current utc
  // DateTime.now() = 2021-01-25 18:49:03.049422
  // DateTime.asUtc() = 2021-01-25 18:49:03.049422
  // DateTime.toUtc() = 2021-01-25 11:49:03.056208Z
  DateTime get asUtc =>
      isUtc ? this : DateTime.utc(year, month, day, hour, minute, second, millisecond, microsecond);

  DateTime get asLocal =>
      !isUtc ? this : DateTime(year, month, day, hour, minute, second, millisecond, microsecond);

  // Convert DateTime to String
  // Month(short) DD HH:MM AM/PM
  String get toDateTimeString => DateFormat('MMM dd h:mm a').format(this);

  // Day, Month DD HH:MM am/pm
  String get toFullDateTimeString => DateFormat('EEEE, MMMM dd h:mm a').format(this);

  // Day, Month DD am/pm
  String get toFullDateString => DateFormat('EEE, yyyy MMMM dd').format(this);

  // HH:MM am/pm
  String get toHMaa => DateFormat('hh:mm aaaa').format(this);

  // HH:MM:SS am/pm
  String get toHHMMSS => DateFormat('hh:mm:ss a').format(this);

  // Month DD
  String get toMMMMdd => DateFormat('MMMM dd').format(this);

  // Month(short) DD
  String get toMMMdd => DateFormat('MMM dd').format(this);

  // YYYY-MM-DD
  String get toYyyymmmdd => DateFormat('yyyy-MMM-dd').format(this);

  // YYYY-MM-DD
  String get toDateOfBirth => DateFormat('yyyy-MM-dd').format(this);

  // To query format: YYYY-MM-DD
  String get toQueryFormat => DateFormat('yyyy-MM-dd').format(this);
}

// Extension for DateTime from String
extension DateTimeStringExtendsion on String {
  // Convert to DateTime by pattern
  // https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html
  DateTime toDateTime({String pattern = 'yyyy-MM-dd HH:mm:ss'}) {
    return DateFormat(pattern).parse(this, true).toLocal();
  }

  String get safe => this;

  String zeroPrefix(int count) {
    if (length >= count) {
      return this;
    } else {
      String builder = '';
      for (int i = 0; i < count - length; i++) {
        builder += '0';
      }
      builder += this;
      return builder;
    }
  }

  int? get parseInt => int.tryParse(this);

  double? get parseDouble => double.tryParse(this);
}

// Extension for duration
extension DurationExtension on Duration {
  Duration get safe => this;

  String get format => toString().split('.').first.padLeft(8, '0');

  // Add zero padding
  String _twoDigits(int n) {
    if (n >= 10) {
      return '$n';
    }
    return '0${max(n, 0)}';
  }

  // hours:minutes:seconds
  String get toHms {
    final String twoDigitHours = _twoDigits(inHours.remainder(24));
    final String twoDigitMinutes = _twoDigits(inMinutes.remainder(60));
    final String twoDigitSeconds = _twoDigits(inSeconds.remainder(60));
    return '$twoDigitHours:$twoDigitMinutes:$twoDigitSeconds';
  }

  // minutes:seconds
  String get toMs {
    final String twoDigitMinutes = _twoDigits(inMinutes.remainder(60));
    final String twoDigitSeconds = _twoDigits(inSeconds.remainder(60));
    return '$twoDigitMinutes:$twoDigitSeconds';
  }
}

// Extension for int
extension DateExtensions on int {
  DateTime get localDateTime => DateTime.fromMillisecondsSinceEpoch(this, isUtc: false);

  DateTime get utcDateTime => DateTime.fromMillisecondsSinceEpoch(this, isUtc: true);

  DateTime asDateTime({TimeZone from = TimeZone.utc}) {
    switch (from) {
      case TimeZone.local:
        return localDateTime;
      case TimeZone.utc:
      default:
        return utcDateTime;
    }
  }

  DateTime asLocal({TimeZone from = TimeZone.utc}) => asDateTime(from: from).asLocal;

  String toTime(BuildContext context, {TimeZone from = TimeZone.utc}) =>
      asDateTime(from: from).toTime(context);

  int localTimeToday({TimeZone from = TimeZone.utc}) =>
      asDateTime(from: from).localTimeToday.millisecondsSinceEpoch;

  int onlyDate({TimeZone from = TimeZone.utc}) =>
      asDateTime(from: from).onlyDate.millisecondsSinceEpoch;

  int onlyTime({TimeZone from = TimeZone.utc}) =>
      asDateTime(from: from).utcTimeFirstDaySinceEpoch.millisecondsSinceEpoch;

  int utcTimeFirstDaySinceEpoch({TimeZone from = TimeZone.utc}) =>
      asDateTime(from: from).utcTimeFirstDaySinceEpoch.millisecondsSinceEpoch;

  Duration asDuration() => Duration(milliseconds: this);
}

Constants

Input Formatters

fromTimezone method: This method from DateTimeHelper class returns UTC datetime. timezone and datetime parameters are mendatory to pass, you can pass daylight true if the datetime is calculated depending on daylight, you can pass custom pattern if you're saving datetime in custom format.

toTimezone method: this method will give desired timezone datetime from UTC. You can pass daylight true if you want the results depending on daylight, you can pass custom pattern if you're saving datetime in custom format.

Get DateTime with zero milliseconds and microsecond

Get DateTime for n days before provided DateTime

Get DateTime for n days after provided DateTime

Get DateTime for the next day start

Get Date only (time is set to zero) (if DateTime type is UTC then return UTC otherwise return local)

Get Month only (time is set to zero and date is set to first) (if DateTime type is UTC then return UTC otherwise return local)

Get Time only

Get UTC Time First Day Since Epoch

Get UTC DateTime

Get Local DateTime

Get Client DateTime

Get MMM DD HH:MM AM/PM formatted string

Get EEEE Month DD HH:MM AM/PM formatted string

Get EEE Month DD formated string

Get HH:MM AM/PM formatted string

Get HH:MM:SS AM/PM formatted string

Get Month(short) Date formated string

Get Year-Month(short)-Date formated string

Get Date of Birth (YYYY-MM-DD) formatted string

Get Custom formatted string

From String to DateTime

Add zeros as a prefix to equalize the length

Parse string to int and double

Get formatted String

Get HH:MM:SS formatted String

Get MM:SS formatted String

Get Local and UTC time from Milliseconds Since Epoch

Get DateTime from Milliseconds Since Epoch

Get DateTime from Milliseconds Since Epoch

fromTimezone method: This method from DateTimeHelper class returns UTC datetime. `timezone` and `datetime` parameters are mendatory to pass, you can pass daylight true if the `datetime` is calculated depending on daylight, you can pass custom `pattern` if you're saving datetime in custom format.

toTimezone method: this method will give desired timezone datetime from UTC. You can pass daylight true if you want the results depending on daylight, you can pass custom `pattern` if you're saving datetime in custom format.