How do I format a date with Dart?

Question

You can use the intl package (installer) to format dates.

For en_US formats, it's quite simple:

import 'package:intl/intl.dart';

main() {
  final DateTime now = DateTime.now();
  final DateFormat formatter = DateFormat('yyyy-MM-dd');
  final String formatted = formatter.format(now);
  print(formatted); // something like 2013-04-20
}

There are many options for formatting. From the docs:

ICU Name                   Skeleton
--------                   --------
DAY                          d
ABBR_WEEKDAY                 E
WEEKDAY                      EEEE
ABBR_STANDALONE_MONTH        LLL
STANDALONE_MONTH             LLLL
NUM_MONTH                    M
NUM_MONTH_DAY                Md
NUM_MONTH_WEEKDAY_DAY        MEd
ABBR_MONTH                   MMM
ABBR_MONTH_DAY               MMMd
ABBR_MONTH_WEEKDAY_DAY       MMMEd
MONTH                        MMMM
MONTH_DAY                    MMMMd
MONTH_WEEKDAY_DAY            MMMMEEEEd
ABBR_QUARTER                 QQQ
QUARTER                      QQQQ
YEAR                         y
YEAR_NUM_MONTH               yM
YEAR_NUM_MONTH_DAY           yMd
YEAR_NUM_MONTH_WEEKDAY_DAY   yMEd
YEAR_ABBR_MONTH              yMMM
YEAR_ABBR_MONTH_DAY          yMMMd
YEAR_ABBR_MONTH_WEEKDAY_DAY  yMMMEd
YEAR_MONTH                   yMMMM
YEAR_MONTH_DAY               yMMMMd
YEAR_MONTH_WEEKDAY_DAY       yMMMMEEEEd
YEAR_ABBR_QUARTER            yQQQ
YEAR_QUARTER                 yQQQQ
HOUR24                       H
HOUR24_MINUTE                Hm
HOUR24_MINUTE_SECOND         Hms
HOUR                         j
HOUR_MINUTE                  jm
HOUR_MINUTE_SECOND           jms
HOUR_MINUTE_GENERIC_TZ       jmv
HOUR_MINUTE_TZ               jmz
HOUR_GENERIC_TZ              jv
HOUR_TZ                      jz
MINUTE                       m
MINUTE_SECOND                ms
SECOND                       s

For non-en_US dates, you need to explicitly load in the locale. See the DateFormat docs for more info. The date_symbol_data_local.dart contains all of the formats for each country/language, if you would like a more in-depth look.

This will work too:

DateTime today = new DateTime.now();
String dateSlug ="${today.year.toString()}-${today.month.toString().padLeft(2,'0')}-${today.day.toString().padLeft(2,'0')}";
print(dateSlug);

You can also specify the date format like stated earlier: https://pub.dev/documentation/intl/latest/intl/DateFormat-class.html

import 'package:intl/intl.dart';
String formatDate(DateTime date) => new DateFormat("MMMM d").format(date);

Produces: March 4

If someone wants to convert a date in string format to some other string format first use DateTime.parse("2019-09-30") then pass it to DateFormat("date pattern").format() like

dateFormate = DateFormat("dd-MM-yyyy").format(DateTime.parse("2019-09-30"));

Reference: Dart - How to change format of simple date string which is in yyyy-MM-dd to dd-MM-yyyy

pubspec.yaml:

dependencies:
  intl:

main.dart:

import 'package:intl/intl.dart'; // for date format
import 'package:intl/date_symbol_data_local.dart'; // for other locales

void main() {
  var now = DateTime.now();
  print(DateFormat().format(now)); // This will return date using the default locale
  print(DateFormat('yyyy-MM-dd hh:mm:ss').format(now));
  print(DateFormat.yMMMMd().format(now)); // print long date 
  print(DateFormat.yMd().format(now)); // print short date 
  print(DateFormat.jms().format(now)); // print time 

  initializeDateFormatting('es'); // This will initialize Spanish locale
  print(DateFormat.yMMMMd('es').format(now)); // print long date in Spanish format
  print(DateFormat.yMd('es').format(now)); // print short date in Spanish format
  print(DateFormat.jms('es').format(now)); // print time in Spanish format
}

Result:

May 31, 2020 5:41:42 PM
2020-05-31 05:41:42
May 31, 2020
5/31/2020
5:41:42 PM
31 de mayo de 2020
31/5/2020
17:41:42

This give you the date like in a social network : ["today","yesterday","dayoftheweek",etc..]

void main() {
      DateTime now = new DateTime(2018,6,26);
      print(date(now));
    }
    
    String date(DateTime tm) {
      DateTime today = new DateTime.now();
      Duration oneDay = new Duration(days: 1);
      Duration twoDay = new Duration(days: 2);
      Duration oneWeek = new Duration(days: 7);
      String month;
      switch (tm.month) {
        case 1:
          month = "january";
          break;
        case 2:
          month = "february";
          break;
        case 3:
          month = "march";
          break;
        case 4:
          month = "april";
          break;
        case 5:
          month = "may";
          break;
        case 6:
          month = "june";
          break;
        case 7:
          month = "july";
          break;
        case 8:
          month = "august";
          break;
        case 9:
          month = "september";
          break;
        case 10:
          month = "october";
          break;
        case 11:
          month = "november";
          break;
        case 12:
          month = "december";
          break;
      }
    
      Duration difference = today.difference(tm);
    
      if (difference.compareTo(oneDay) < 1) {
        return "today";
      } else if (difference.compareTo(twoDay) < 1) {
        return "yesterday";
      } else if (difference.compareTo(oneWeek) < 1) {
        switch (tm.weekday) {
          case 1:
            return "monday";
          case 2:
            return "tuesday";
          case 3:
            return "wednesday";
          case 4:
            return "thursday";
          case 5:
            return "friday";
          case 6:
            return "saturday";
          case 7:
            return "sunday";
        }
      } else if (tm.year == today.year) {
        return '${tm.day} $month';
      } else {
        return '${tm.day} $month ${tm.year}';
      }
    }