intl package and date formatting strange behaviour

Question

I start to use intl package in my dart project. After start to use this package i use this code:

  DateTime now = new DateTime.now();
  var formatter = new DateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
  String nowFormatted = formatter.format(now);

And it works correctly. After i use intl i obtain this message in log:

Uncaught LocaleDataException: Locale data has not been initialized, call initializeDateFormatting(<locale>).

I cannot understand why i should pass locale in this code snippet

it is contained in date_format.dart. in the header of the file i see part of intl; — Andrea Bozza, Mar 23 '16 at 09:25
@ThierryTemplier the Dart `intl` is not related to the JS `intl`. — Günter Zöchbauer, Mar 23 '16 at 09:29
Your code prints `2016-03-23T10:39:03Z` for me. Which line causes your exception? What version of `intl` is listed in your `pubspec.lock` file? — Günter Zöchbauer, Mar 23 '16 at 09:39

score 55 · Answer 1 · edited Jun 20 '20 at 09:12

55

intl: ^0.15.7

I've the same issue to the current Intl version so I've solved with

these imports:

import 'package:intl/intl.dart';
import 'package:intl/date_symbol_data_local.dart';

and the code:

initializeDateFormatting();
DateTime now = DateTime.now();
var dateString = DateFormat('dd-MM-yyyy').format(now);
final String configFileName = 'lastConfig.$dateString.json';

edited Jun 20 '20 at 09:12

Community

1
1

answered Feb 12 '19 at 09:19

Alessandro Ornano

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3

This `initializeDateFormatting()` with no arguments does not work in latest version `intl: ^0.16.1`. Any solution? – Faizan Mubasher Sep 15 '20 at 05:09
@FaizanMubasher Have you tried for example something like : `initializeDateFormatting('de_DE', null)` – Alessandro Ornano Sep 15 '20 at 08:46
7

@FaizanMubasher, I had the same sure. Make sure that you have this import: `import 'package:intl/date_symbol_data_local.dart';`, because `initializeDateFormatting` is included is several files. – Vsevolod Krasnov Nov 09 '20 at 08:55
It must be `date_symbol_data_local` (2nd parameter ignored) not `date_symbol_data_file`! – Nigel Sheridan-Smith Apr 08 '21 at 20:48
1

`initializeDateFormatting` is a future, so you must `await initializeDateFormatting()` or `initializeDateFormatting().then((_) => runMyCode())` to avoid unexpected results (otherwise it might not actually finish initialising before you use DateFormat) – James Allen Aug 19 '21 at 14:42
It's required two arguments compulsory. – Pratik Butani Nov 24 '21 at 11:26
@PratikButani In the far 2019 the release 0.15.7 didnt need two args. So why vote negative a correct answer that worked great? – Alessandro Ornano Nov 29 '21 at 14:45
Definitely not worked great. but do you think this answer is useful now? – Pratik Butani Nov 30 '21 at 04:58
@PratikButani Yes it is. There is always people who need the correct code for old library release. Thats the stackoverflow phylosophy , you should know it. – Alessandro Ornano Nov 30 '21 at 09:16
@JamesAllen not necessarily, it just assigns a mapping to variable:) – Nickolay Savchenko Feb 15 '22 at 02:35

rubStackOverflow · Answer 2 · 2019-11-30T02:08:03.573

23

Verify your imports:

import 'package:intl/date_symbol_data_local.dart';
import 'package:intl/intl.dart';

Set initializeDateFormatting according to your language, example:

initializeDateFormatting('pt_BR', null);

edited Nov 30 '19 at 02:08

answered Nov 30 '19 at 01:50

rubStackOverflow

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2
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score 22 · Answer 3 · edited Jul 26 '20 at 07:07

22

If you encounter this problem, write initializeDateFormatting('az'); top of "Material App". I searched for 1 hour and nobody wrote it clearly.

it is really solved.

edited Jul 26 '20 at 07:07

FarZad

463
3
19

answered Jul 25 '20 at 16:15

Söhrab Vahidli

587
7
10

score 13 · Answer 4 · answered Jan 23 '21 at 19:05

13

Use this function in main

initializeDateFormatting();

and import like this

import 'package:intl/date_symbol_data_local.dart';

answered Jan 23 '21 at 19:05

umutckmk

131
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score 11 · Answer 5 · edited Dec 28 '20 at 10:55

11

I have solved this use in this way:

DateTime now = new DateTime.now();
var formatter = new DateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", 'en');
String nowFormatted = formatter.format(now);

But I have to make this to my dart file used to configure itnl support:

library translation_helper;

import 'dart:async';
import 'package:intl/date_symbol_data_local.dart';
import '../../resources/messages_all.dart';


void setupLanguage(){
  //var germanDatesFuture = initializeDateFormatting('de_DE', null);
  var enDatesFuture = initializeDateFormatting('en', null);
  var germanMessagesFuture = initializeMessages('de');
  var englishMessagesFuture = initializeMessages('en');
  var italianMessagesFuture = initializeMessages('it');
  var polishMessagesFuture = initializeMessages('pl');
  Future
      .wait([
    enDatesFuture,
    germanMessagesFuture,
    englishMessagesFuture,
    italianMessagesFuture,
    polishMessagesFuture
  ]);
}

Before I was missing:

 var enDatesFuture = initializeDateFormatting('en', null);

For more info I use:

dart 1.15.0
intl 0.12.7

edited Dec 28 '20 at 10:55

Ahmed Ashour

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answered Mar 23 '16 at 09:47

Andrea Bozza

1,374
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Interesting. Why do you need that while it worked for me without. What OS are you using? – Günter Zöchbauer Mar 23 '16 at 09:56
Boring OSX last version -_- – Andrea Bozza Mar 23 '16 at 10:01
3

Yes, you have to initialize the format for a particular locale before you can use it. In some cases the data is already loaded, but in others (most commonly messages, where the data can take up a lot of space) it might need to load the data before it can be used. Typically you wouldn't initialize all the messages for every locale, just the one for your user's locale. – Alan Knight Mar 24 '16 at 17:33
1

Where do you put the configuration? – Giraldi Oct 30 '18 at 10:11

score 6 · Answer 6 · answered Feb 05 '20 at 10:48

There's no need to call initializeDateFormatting directly from your code. Just call load method of app's localization delegates.

So you specify delegates like this:

final localizationsDelegates = <LocalizationsDelegate>[
  AppLocalizationsDelegate(),
  GlobalMaterialLocalizations.delegate,
  GlobalWidgetsLocalizations.delegate,
  CupertinoLocalizationsDelegate()
];

...

  MaterialApp(
    localizationsDelegates: localizationsDelegates,
  )

And pre-load them with system's locale:

import 'dart:ui' as ui;

...

for (final delegate in localizationsDelegates) {
  await delegate.load(ui.Locale(ui.window.locale.languageCode));
}

score 6 · Answer 7 · edited Jun 15 '20 at 11:37

In your pubspec.yaml, add this dependencie package: intl:
In your highest StatefulWidget (in your dart file), add these imports:

    import 'package:intl/intl.dart';
    import 'package:intl/date_symbol_data_local.dart';

In its State, override initState add :

      @override
      void initState() {
        super.initState();
        initializeDateFormatting(); //very important
      }

And the code:

     DateTime now = new DateTime.now();
     var formatter = new DateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
     String nowFormatted = formatter.format(now);

score 5 · Answer 8 · answered Nov 15 '19 at 11:23

5

My issue was that I was getting error specifically for the "en_US" Locale even when I was not particularly using it. But I solved it by:

initializeDateFormatting('en', null);
initializeDateFormatting('en_US,', null);

answered Nov 15 '19 at 11:23

Ndivhuwo

280
2
10

score 5 · Answer 9 · edited Mar 31 '22 at 00:13

5

In your class with MaterialApp add this code

import 'package:intl/date_symbol_data_local.dart';

@override
  void initState() {
    // TODO: implement initState
    super.initState();`enter code here`
    initializeDateFormatting();
  }

edited Mar 31 '22 at 00:13

Alex Weitz

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answered Mar 30 '22 at 07:49

shams7

71
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4

this threw: "Unsupported operation: Cannot modify unmodifiable map" error... am stuck with this issue now... – HaKim Apr 06 '22 at 17:01
@HaKim you need to add above mentioned code in the widget in which you are using Intl package – Muhammad Faizan Nov 17 '22 at 10:22

score 1 · Answer 10 · answered Oct 28 '20 at 08:16

To initialize the date format as per the system locale.

import 'package:intl/intl_standalone.dart'; // For standlone app
import 'package:intl/intl_browser.dart'; // For standlone app
import 'package:intl/date_symbol_data_local.dart';
...
await initializeDateFormatting(await findSystemLocale(), null);

score 0 · Answer 11 · answered Oct 11 '19 at 22:11

I got the same error. But, only when switching between locales ('en' and 'si') within the app. None of the other solutions worked for me. So I just came up with this dumbest solution, and it worked. Just wrapped date-formatting in a try-catch block while initializeDateFormatting() is being called inside the catch block

String  date(DateTime date, String _languageCode) {
    try {
        var formatter = new DateFormat.yMMMMd(_languageCode);
        return formatter.format(date);
    } catch(e) {
        initializeDateFormatting();
        var formatter = new DateFormat.yMMMMd(_languageCode);
        return formatter.format(date);
    }
}

score 0 · Answer 12 · answered Dec 17 '22 at 22:31

0

Depending on intl: ^0.18.0

Just add this line in the method that listens to each time the locale changes

Intl.defaultLocale = languageCode;

package: https://pub.dev/packages/intl

answered Dec 17 '22 at 22:31

Adel N. Daniel

99
5

intl package and date formatting strange behaviour

12 Answers12

intl: ^0.15.7

Depending on intl: ^0.18.0

Linked