Internationalization and localization support

<img src="https://avatars.githubusercontent.com/u/3476088?v=3" align="left" width="96" height="96"hspace="10"> Issue by alan-knight Originally opened as dart-lang/sdk#8110

We currently don't have a mechanism for finding the locale from windows. The mechanism of asking systeminfo and parsing the result was incredibly slow and didn't work properly anyway. I believe we would need to add some sort of native API call to get the information reasonably.

This causes issues in https://dart-review.googlesource.com/c/sdk/+/224520, although maybe we just need a slightly newer version pulled into the SDK. But we should enable actual null safety anyway.

Create a way of parse date time format without delimiter without break change.

test('No delimiter 4 digits year', () {
    final timestamp = "20190614071930";
    final result = DateFormat('yyyyMMddHHmmss').parseNoDelimiter(timestamp);
    expect(result, DateTime(2019, 06, 14, 07, 19, 30));

A date time format like 'yyyyMMddHHmmss' now can be parsed calling DateFormat(String).parseNoDelimiter(String)

close #452 close #210 close #445 close #278

import 'package:intl/intl.dart';
final dateFormat = new DateFormat("d/M/y H:m:s");
print(dateFormat.parse("01/02/16 12:11:12").year);

This code results in a year of 0016 and not 2016. Same thing happens whether I use y or yy in the format. Unfortunately it's tricky to fix this, because you can't even .add 2000 years, because the Duration class only goes up to days!

Other languages make assumptions about two-digit years being 19/20; it probably makes sense to do the same.

From @ajsergeev on July 21, 2015 8:28

v,z patterns don't work because:

String formatTimeZoneId(DateTime date) { // TODO(alanknight): implement time zone support throw new UnimplementedError(); }

String formatTimeZone(DateTime date) { throw new UnimplementedError(); }

String formatTimeZoneRFC(DateTime date) { throw new UnimplementedError(); }

Copied from original issue: dart-lang/sdk#23879

Given this "yyyyMMddHHmmss" format: DateFormat("yyyyMMddHHmmss").format(DateTime.now()); gives a nice string like: "20190405140723" as I would expect.

Now reversely parsing... DateFormat("yyyyMMddHHmmss").parse("20190405140723"); throws the message "Trying to read MM from 20190405140723 at position 14"

It seems the parser consumes the whole string (after the 2019) while searching for some separator that I don't have in the format.

Shouldn't parse and format be reversible?

I've tried with parseLoose and parseStrict: same result. Using intl version: "0.15.8"

  String themeDisplayName(String themeName) {
    switch (themeName) {
      case 'origin':
        return Intl.message('Origin', name: AppTheme.origin.name);
      case 'purple':
        return Intl.message('Purple', name: AppTheme.purple.name);
    ...

To make refactoring easier and prevent accidental mismatches.

used constants

class AppTheme {
  static const AppTheme origin = const AppTheme('origin');
  static const AppTheme purple = const AppTheme('purple');
  ...

  final String name;
}

Currently I get

Skipping invalid Intl.message invocation
    <Intl.message('Origin', name: AppTheme.origin.name)>
    reason: The 'name' argument for Intl.message must be a string literal
    from File: 'lib/localization/localizations.dart'    line: 33, column: 16
Skipping invalid Intl.message invocation
    <Intl.message('Purple', name: AppTheme.purple.name)>
    reason: The 'name' argument for Intl.message must be a string literal
    from File: 'lib/localization/localizations.dart'    line: 35, column: 16

Hello,

I wanted to have decentralized traductions instead of having them transformed/generated to dart. But I find myself totally blocked by the intl API and way of doing things.

Take this example: String complex(String name, String name2) => Intl.message('$name2 love $name', args: [name, name2], name: 'complex');

In ARB format it will be generated like this:

"complex": "{name2} love {name}",
"@complex": {
  "type": "text",
  "placeholders": {
    "name": {},
    "name2": {}
  }
},

To be able to find translations Intl is using MessageLookup under the hood, so I was trying to extends it and make my own lookup based on ARB I have downloaded.

For that we need to implement this method:

String? lookupMessage(String? messageText, String? locale, String? name, List<Object>? args, String? meaning, {MessageIfAbsent? ifAbsent}) {

So here I'll receive the sentence "{name2} love {name}", and now I'm blocked, because I have a list of args but no way to find which one is name and which one is name2.

I there any workaround or other way I can achieve this ?

hi, I have two translations.dart one for each project and another one for the commons translation, I would like to use 2 translations.dart in one project (project_translation.dart and common_translation.dart), is it possible?

It seems that intl gets in a corrupted state if a DateFormat variable is used before localization is initialized in Flutter. This bug is making Firebase authentication fail on Flutter Web: https://github.com/FirebaseExtended/flutterfire/issues/3374 .

A complete MWE to reproduce this bug is available at https://github.com/knuesel/dateformat_bug : it's a vanilla Flutter app (from flutter create) with a few lines of code added to enable localization using the new Flutter localization process.

Here's the essence of the MWE:

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

final format = DateFormat('EEE, d MMM yyyy HH:mm:ss', 'en_US');
final date = 'Fri, 25 Sep 2020 12:39:53 GMT';

void main() {
  print('@ Parsing date in main()...');
  print(format.parse(date)); // Commenting this makes the other parse call work
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      localizationsDelegates: AppLocalizations.localizationsDelegates,
      supportedLocales: AppLocalizations.supportedLocales,
      ...
    );
  }
}

class _MyHomePageState extends State<MyHomePage> {
...
  @override
  Widget build(BuildContext context) {
    print('@ Parsing date in widget build...');
    print(format.parse(date));  // This throws an exception

    return ...;
  }
}

This code throws an exception:

I/flutter (28125): @ Parsing date in main()...
I/flutter (28125): 2020-09-25 12:39:53.000
I/flutter (28125): @ Parsing date in widget build...

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following FormatException was thrown building MyHomePage(dirty, state: _MyHomePageState#ff885):
Trying to read EEE from Fri, 25 Sep 2020 12:39:53 GMT at position 0

The relevant error-causing widget was: 
  MyHomePage file:///home/j/temp/dateformat/dateformat_bug/lib/main.dart:40:13
When the exception was thrown, this was the stack: 
#0      _DateFormatField.throwFormatException (package:intl/src/intl/date_format_field.dart:87:5)
#1      _DateFormatPatternField.parseField (package:intl/src/intl/date_format_field.dart:337:7)
#2      _DateFormatPatternField.parse (package:intl/src/intl/date_format_field.dart:250:5)
#3      DateFormat._parse (package:intl/src/intl/date_format.dart:374:13)
#4      DateFormat.parse (package:intl/src/intl/date_format.dart:303:7)

As you can see, parsing the same date string with the same DateFormat variable works in main(), but throws when it's run after Flutter localization has been enabled.

The second parse call works if we remove the first parse in main.

Both calls work if we remove the line localizationsDelegates: AppLocalizations.localizationsDelegates.

The docs (including ICU docs) say that the k pattern should give "hour in day (1~24)".

https://github.com/dart-lang/intl/blob/4b385517037485e3243d6915453215af315add27/lib/src/intl/date_format.dart#L154

However I cannot seem to obtain 24; all I can get is 0:

final date = DateTime(2019, 6, 10, 0, 30);
print(DateFormat('k:mm').format(date)); // result: 0:30
print(DateFormat('kk:mm').format(date)); // result: 00:30

I would have expected both of these to give 24:30.

The abbreviated month is not being used in es_US locale when using the skeleton pattern.

Try this code:

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

void main() {
  initializeDateFormatting();
  print(DateFormat('d MMM yyyy', 'es_US').format(DateTime.now()));
  print(DateFormat.yMMMd('es_US').format(DateTime.now()));
}

It prints:

21 dic. 2022
21 de diciembre de 2022

Note that instead using es_ES as the locale produces the expected result.

Describe the bug When upgrading to 0.18.0, I get the following error:

[APP_NAME] flutter pub get
Running "flutter pub get" in APP_NAME...                          
Because APP_NAME depends on flutter_localizations from sdk which depends on intl 0.17.0, intl 0.17.0 is required.
So, because APP_NAME depends on intl ^0.18.0, version solving failed.
pub get failed (1; So, because APP_NAME depends on intl ^0.18.0, version solving failed.)
exit code 1

To Reproduce

• Upgrade intl to 0.18.0.
• Run flutter pub get

System info Can not, because flutter pub get failed.

Versions

• Flutter: 3.3.10
• environment sdk: ">=2.18.6 <3.0.0"
• flutter_localizations: sdk: flutter

NumberFormat.simpleCurrency(locale: 'en_US', decimalDigits: 2, name: 'GBP').format(-2345) Results in: -£2,345.00 (Correct)

NumberFormat.compactSimpleCurrency(locale: 'en_US', decimalDigits: 2, name: 'GBP').format(-2345) Results in: £-2.35K (Incorrect, the minus sign should be before the pound sign)

Executing DateFormat.format on compute throws a LocaleDataException, is this expected behavior?

Future<void> main() async {
  await initializeDateFormatting('ja_JP');
  runApp(const MyApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(),
    );
  }


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

  static final DateFormat _formatter = DateFormat.yMd('ja');

  void _convert(String date) {
    print(_formatter.parse(date));
  }

  Future<void> _compute() async {
    // _convert('2022/01/01 00:00'); <- work correctly
    compute(_convert, '2022/01/01 00:00'); <- throw LocaleDataException
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('compute'),
      ),
      body: Center(child: Text('compute test')),
      floatingActionButton: FloatingActionButton(
        onPressed: _compute,
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

% flutter --version
Flutter 3.3.4 • channel stable • https://github.com/flutter/flutter.git
Framework • revision eb6d86ee27 (6 weeks ago) • 2022-10-04 22:31:45 -0700
Engine • revision c08d7d5efc
Tools • Dart 2.18.2 • DevTools 2.15.0

intl: ^0.17.0

If you use a format like "#0.######################################" and then format the number "1" the result is "1e+38".

NumberFormat class Line 617 power = pow(10, fractionDigits) as int;

If fractionDigits is bigger than 20, this bug will happen. power will be anything with e+?? and as a result the _formatFractionPart just adds it back to the number, as it only excludes non zero characters.