Without build.yaml config command flutter pub run fast_i18n generate this class:

But when I add build.yaml with:

targets:
  $default:
    builders:
      fast_i18n:
        options:
          base_locale: cs
          translate_var: translate
          key_case: camel
          string_interpolation: double_braces

so it generate:

Where name is undefined variable because $ symbol is not escaped by \$.

My strings.i18n.json is:

{
  "title": "Scanner pro vážení balíků",
  "scanner_informations": "Scanner informations",
  "scale_informations": "Scale informations",
  "hello": "Hello $name",
  "save": "Save",
  "login": {
    "fail": "Logged in failed"
  }
}

With the latest build runner, next error occurs during code generation:

../../../../.pub-cache/hosted/pub.dartlang.org/analyzer-1.5.0/lib/src/error/best_practices_verifier.dart:266:50: Error: The property 'displayString' is defined in multiple extensions for 'TargetKind' and neither is more specific.
 - 'TargetKind' is from 'package:meta/meta_meta.dart' ('../../../../.pub-cache/hosted/pub.dartlang.org/meta-1.7.0/lib/meta_meta.dart').
Try using an explicit extension application of the wanted extension or hiding unwanted extensions from scope.
        var kindNames = kinds.map((kind) => kind.displayString).toList()
                                                 ^^^^^^^^^^^^^
../../../../.pub-cache/hosted/pub.dartlang.org/analyzer-1.5.0/lib/src/error/best_practices_verifier.dart:1978:14: Context: This is one of the extension members.
  String get displayString {
             ^^^^^^^^^^^^^
../../../../.pub-cache/hosted/pub.dartlang.org/meta-1.7.0/lib/meta_meta.dart:91:14: Context: This is one of the extension members.
  String get displayString {
             ^^^^^^^^^^^^^
../../../../.pub-cache/hosted/pub.dartlang.org/analyzer-1.5.0/lib/src/error/best_practices_verifier.dart:268:36: Error: The getter 'commaSeparatedWithOr' isn't defined for the class 'List<dynamic>'.
 - 'List' is from 'dart:core'.
Try correcting the name to the name of an existing getter, or defining a getter or field named 'commaSeparatedWithOr'.
        var validKinds = kindNames.commaSeparatedWithOr;
                                   ^^^^^^^^^^^^^^^^^^^^
../../../../.pub-cache/hosted/pub.dartlang.org/analyzer-1.5.0/lib/src/error/best_practices_verifier.dart:1978:14: Error: A non-null value must be returned since the return type 'String' doesn't allow null.
  String get displayString {
             ^
             ```

To set a default language, a configuration was made in build.yaml file, where base_locale was set to hr

targets:
  $default:
    builders:
      fast_i18n:
        options:
          base_locale: hr #<<<<<
          fallback_strategy: base_locale
          input_directory: lib/core/i18n
          input_file_pattern: .i18n.json
          output_directory: lib/core/i18n
          output_file_pattern: .g.dart
          translate_var: tr
          enum_name: AppLocale
          translation_class_visibility: private

Configuration along with generated dart code is as following:

The issue is at the startup when translation is fetched from json file, it does not get translation from default language/base_locale as it should, but rather it displays English translation (Loyalty club):

Text(tr.landing.benefitsClub), // displays "Loyalty club"

I am attaching the image:

Motivation
Making migrations easier

Developer Experience
Add new command flutter pub run fast_i18n migrate-arb source.arb destination.i18n.json

Are there plans to support plural forms?

Motivation
To reduce asset size, developers can extract the translations to the server.
The translations will be fetched at runtime.

Developer Experience
Because every key needs to be known at compile time, the base translations must be available.

// strings.i18n.json
{
  "greet": "Welcome {name}"
}

Now load a locale:

// your logic, represents ONE locale!
Map fetchFromServer() {
  return {
    'greet': 'Hello {name}'
  }
}

// via LocaleSettings
void example1() {
  String a = t.greet(name: 'Tom'); // "Welcome Tom"

  Map data = fetchFromServer(); 
  LocaleSettings.loadCustom(data); // the new load function
  String b = t.greet(name: 'Tom'); // "Hello Tom"
}

// via dependency injection
void example2() {
  String a = t.greet(name: 'Tom'); // "Welcome Tom"

  Map data = fetchFromServer();
  final t2 = AppLocaleUtils.buildCustom(data); // the new build function
  String b = t2.greet(name: 'Tom'); // "Hello Tom"
}

This will blow up the generated file. Therefore, this should be opt-in.

targets:
  $default:
    builders:
      fast_i18n:
        options:
          contexts:
            dynamic_translations: true # enable this feature

After migrating to 5.0.0 the generated d.dart file is not compiling in my project. It is throwing a type errors

lib/l10n/messages.g.dart:136:59: Error: 'PluralResolver' isn't a type.
	static void setPluralResolver({required String language, PluralResolver? cardinalResolver, PluralResolver? ordinalResolver}) {
	                                                        ^^^^^^^^^^^^^^
lib/l10n/messages.g.dart:136:93: Error: 'PluralResolver' isn't a type.
	static void setPluralResolver({required String language, PluralResolver? cardinalResolver, PluralResolver? ordinalResolver}) {
	                                                                                          ^^^^^^^^^^^^^^
lib/l10n/messages.g.dart:137:33: Error: Getter not found: '_pluralResolversCardinal'.
		if (cardinalResolver != null) _pluralResolversCardinal[language] = cardinalResolver;
		                             ^^^^^^^^^^^^^^^^^^^^^^^^
lib/l10n/messages.g.dart:138:32: Error: Getter not found: '_pluralResolversOrdinal'.
		if (ordinalResolver != null) _pluralResolversOrdinal[language] = ordinalResolver;

Here's my configuration in build.yaml

targets:
  $default:
    builders:
      fast_i18n:
        options:
          input_directory: res/l10n
          output_directory: lib/l10n
          translation_class_visibility: public

When trying to access translation value by dynamic key I'm getting error that says

_The operator '[]' isn't defined for the type 'StringsLanguagesHr'.
Try defining the operator '[]'

tr.languages['hr'] // error here

// File: strings.i18n.json

  "languages": {
    "hr": "Hrvatska",
    "us": "SAD"
  }

Is it possible to change (or customize) the "t" access variable? e.g. t.my.string.path becomes i18n.my.string.path?

Motivation
Sometimes, the translations will be fetched from the server. For example, a news page where the strings are not known during compile-time.

Developer Experience
For overwritable nodes: Create a new function void overwriteTranslations({ <attributes> }) which sets the new translations.

String before = t.pages.newsPage.title;

// current locale
t.pages.newsPage.overwriteTranslations(
  title: 'New Title',
  content: fetchedContent,
);

String after = t.pages.newsPage.title; // 'New Title'

// custom locale
AppLocale.fr.translations.pages.newsPage.overwriteTranslations(
  title: fetchedTitle,
  content: fetchedContent,
);

The selected nodes are specified in build.yaml similar to maps:

targets:
  $default:
    builders:
      fast_i18n:
        options:
          overwritable:
            - pages.newsPage

When I try to generate the strings.g.dart file using the build_runner, I get the following error:

[SEVERE] fast_i18n:i18nBuilder on lib/presentation/core/i18n/strings.i18n.json:

This builder requires Dart inputs without syntax errors.
However, package:brickfact/presentation/core/i18n/strings.i18n.json (or an existing part) contains the following errors.
strings.i18n.json:1:1: Expected a method, getter, setter or operator declaration.

When I try with the flutter pub run fast_i18n command it works without issues. It would however be nice if it works with the build_runner, even if it is slower, as this command is always running. Is there a way to make this work?

Motivation
I use several packages that depend on code generation. So I have to run the code generation quite often. And each time the timestamp in the strings.g.dart updates. I then have to revert that file, because at first glance in the git log it looks like the localization has changed, even though nothing has changed.

So it would be a nice QOL improvement :)

When using auto plural detection, then pluralization resolvers are not rendered.

Configuration:

fast_i18n:i18nBuilder:
  enabled: true
  options:
   pluralization:
      auto: cardinal

Reason:
So we can comment.

With current json implementation, it's impossible to comment.
We need to comment so the person who actually translate the text can have context.

Hi, thanks for your package, it's awesome!)

But it would be great if we will have possibility to set in and out file directories and in files regex.
For example in my case I store my locale files in assets/locale and them have names {languageName}.json
I think it's not logical to mix them with code files in lib directory because it's assets.

So it would be nice if I could set in dir => assets/locale, out dir => lib/i18n and files pattern => **.json

Btw also I think dependency of devicelocale is reduntant because it haven't implementation for flutter desktop, but can be checked easy just like that
final locale = WidgetsBinding.instance.window.locale;

iso 3166 country code of India have problem, as below:

My project has over 7k source keys and over 14 languages. This makes the generated file over 2.5 MB in size, thus the IDE has problems caching/indexing the file. Maybe it is better to split the classes into separate files?

Release 5.0.0

This release mostly focuses on simplifications of build.yaml.

Builder Name

Simplify fast_i18n:i18nBuilder to fast_i18n.

targets:
  $default:
    builders:
      fast_i18n: # no more "fast_i18n:i18nBuilder"
        options:
          base_locale: fr

Plural Auto Detection

Setting auto: cardinal by default applies to most projects. This means that you don't need the pluralization section at all in your build.yaml!

targets:
  $default:
    builders:
      fast_i18n:
        options:
          pluralization:
            auto: cardinal # default

Fallback Strategy

The previous default mode strict has been renamed to none, This makes more sense because there is no fallback strategy at all.

targets:
  $default:
    builders:
      fast_i18n:
        options:
          fallback_strategy: none # was "strict"

Paths & Key Case

Only for developers using both key_case and any path related feature (maps, pluralization paths, context paths).

Paths must be cased according to key_case if specified.

 {
  "a_b": {
    "hi": "hi"
  }
}

targets:
  $default:
    builders:
      fast_i18n:
        options:
          key_case: camel # this forces every other path also be in camel case
          maps:
            - aB

Null Safety

Null safety is must have. This will simplify the code base.

Can you please explain why do I get this warning?

Let's say I want next string "{number}mm"
With that library it's only possible to do next:
"$number mm"
But I really don't want to use space here
How to handle such a case without splitting it into two strings

During generation output_directory is ignored and input_directory is used instead.

fast_i18n: 5.12.0

in build.yaml I turned off pluralization but in the generated file I have unused private methods _pluralCardinalEn and _pluralOrdinalEn.

Is it possible not to generate the mentioned methods?

Hi thanks for the code generator! However, I need it in pure Dart packages (as well as Flutter packages), but the generator generates code with import 'package:flutter/widgets.dart';, which is impossible for dart packages.

Talking about #63, maybe we can create two supportive packages (instead of one), one for dart, one for flutter-specific features.

When compiling I get the following error:

/D:/flutter/.pub-cache/hosted/pub.dartlang.org/fast_i18n-3.0.3/lib/fast_i18n.dart:13:46: Error: Method 'toLanguageTag' cannot be called on 'Locale?' because it is potentially null.
 - 'Locale' is from 'dart:ui'.
Try calling using ?. instead.
      WidgetsBinding.instance?.window.locale.toLanguageTag();

The issue is resolved modifying:

class FastI18n {
  static const _localePartsDelimiter = '-';

  /// Returns the locale string used by the device.
  static String? getDeviceLocale() =>
-      WidgetsBinding.instance?.window.locale.toLanguageTag();
+     WidgetsBinding.instance?.window.locale?.toLanguageTag();

  /// Returns the candidate (or part of it) if it is supported.
  /// Fallbacks to base locale.
  /// Please note that locales are case sensitive.
  static String selectLocale(
      String candidate, List<String> supported, String baseLocale) {
    // normalize
    candidate = Utils.normalize(candidate);

My config is:
$ cat pubspec.yaml

environment:
    sdk: '>=2.12.0 <3.0.0'

$ flutter doctor

[√] Flutter (Channel stable, 2.0.4, on Microsoft Windows [Version 10.0.19042.867], locale en-BE)

Is it possible to verify this issue?

Hi @Tienisto,
Thanks for making this amazing library, I want to update the language for the whole app from the settings page.
I used LocaleSettings.setLocale('es'); in main page and it's working fine.
But I'm using MVVM architecture and I want to change the language from my view-model any suggestions from your side.

Is it possible to support csv files also? I think it is the easiest way to create and update translations.

I am attaching the image of the hint:

Thank you for this helpful package.

I've noticed that if I use {snake_case} in my translation strings, that the corresponding method does not apply camel case to the method's named parameters. For example, given the following translation string:

{
  "visit_status": "{status_text} at {when}"
}

I would expect the following method signature to be generated with the named parameter statusText having camel case applied.

  String visitStatus({required Object statusText, required Object when}) => '$statusText at $when';

However, the following method signature is generated where the snake case has not been converted to camel case.

  String visitStatus({required Object status_text, required Object when}) => '$status_text at $when';

My build.yaml file is:

targets:
  $defaults:
    builders:
      fast_i18n:
        options:
          fallback_strategy: base_locale
          input_directory: lib/localizations
          output_directory: lib/localizations
          key_case: camel
          string_interpolation: braces

Hi! I am using this package for my app but I also have older package with localization using intl - like MyPackageLocalizations.of(context).blah.
I have noticed that when I use LocaleSettings.setLocale(), it doesn't set context's locale and so strings provided by that package are not translated.
Confirmed when I set MaterialApp(locale: myLocale), it works.

Do I need to set context's locale by myself?

Tried the steps in the description. I have 2 json files, fast-i18n dependencies are added,flutter packages pub run build_runner build produces no output (except those ones by Hive which also uses build_runner).

Contents of strings.i18n.json

{
  "entries": "esntries",
  "search": "Search",
  "type-in": "Type-in text below"
}

Part of the pubspec.yaml:

version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  
  provider: ^4.0.2
  shared_preferences: 
  flutter_html: ^1.0.0
  hive: ^1.4.1+1
  hive_flutter: ^0.3.0+2
  sprintf: "^4.0.0"
  archive: ^2.0.13
  flutter_sticky_header: ^0.4.2
  reorderables: ^0.3.2
  double_back_to_close_app: ^1.2.0
  fluttertoast: ^7.0.1
  file_picker: ^1.13.0+1
  fast_i18n: ^1.4.0

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.3

dependency_overrides:
  flutter_svg: 0.18.0 #Flutter 1.20 and flutter_html issue
  path: 1.6.4
  hive: # custom version remove box key assertion to be ASCII string not greater than 255 chars
    path: ./plugins/hive-1.4.1+1/
  reorderables:
    path: ./plugins/reorderables-0.3.2/

dev_dependencies:
  flutter_test:
    sdk: flutter
  hive_generator: ^0.7.0+2
  build_runner: ^1.10.0
  flutter_launcher_icons: ^0.7.3
  flutter_native_splash: ^0.1.9

And that's flutter packages pub run build_runner build output:

[INFO] Generating build script...
[INFO] Generating build script completed, took 549ms

[WARNING] Deleted previous snapshot due to missing asset graph.
[INFO] Creating build script snapshot......
[INFO] Creating build script snapshot... completed, took 15.0s

[INFO] Initializing inputs
[INFO] Building new asset graph...
[INFO] Building new asset graph completed, took 902ms

[INFO] Checking for unexpected pre-existing outputs....
[INFO] Found 1 declared outputs which already exist on disk. This is likely because the`.dart_tool/build` folder was deleted, or you are submitting generated files to your source repository.
[SEVERE] Conflicting outputs were detected and the build is unable to prompt for permission to remove them. These outputs must be removed manually or the build can be run with `--delete-conflicting-outputs`. The outputs are: lib/models/indexedDictionary.g.dart

Is it possible to have pluralization with multiple fields through linked translations? For example, if we have a strings.i18n.yaml like:

login:
  passwordInvalidFields:
    characters:
      one: $count character
      other: $count characters
    symbols:
      one: $count symbol
      other: $count symbols
  passwordInvalid: Password must be at least @:login.passwordInvalidFields.characters long with at least @:login.passwordInvalidFields.symbols

It will generate code for this, but then there is only one named count parameter: t.login.passwordInvalid(count: _passwordMinLength) so we can't specify the separate numbers for the number of characters and symbols. If instead the YAML is changed to:

login:
  passwordInvalidFields:
    characters:
      one: $numCharacters character
      other: $numCharacters characters
    symbols:
      one: $numSymbols symbol
      other: $numSymbols symbols
  passwordInvalid: Password must be at least @:login.passwordInvalidFields.characters long with at least @:login.passwordInvalidFields.symbols

then t.login.passwordInvalid will have the numCharacters and numSymbols parameters but then also have a count named parameter as well. Is it possible to use a named parameter other than $count for pluralization? What is the right way to do pluralization of multiple items within a single sentence?

Of course, readme is good.
But a real project with example must be a plus I think

For example, if someone has issues with lib he always can run that example and play with it
Sometimes it's really difficult to understand why it not generated.
As for me it was .i18n suffix, and I think I'm not the only one who has such issues

Hello, I experiment with namespaces for split my one input file into more files.
I had in strings.i18n.json this json structure:

{
  "core": {
    ...
  },
  "app": {
    "title": "Example App",
    ...
  },
  "auth": {
    ...
  },
  "barcode_registration": {
    ...
  }
}

And I split it into this folder structure:

But when I run flutter pub run fast_i18n command so it generate translations only for core, app and auth but
translations in barcode_registration section is not generated..:

Probably there is a problem with _ and it doesn't create barcodeRegistration property.

Can you fix it please?

Here is my build.yaml configuration:

targets:
  $default:
    builders:
      fast_i18n:
        options:
          base_locale: cs
          translate_var: translate
          key_case: camel
          key_map_case: camel
          param_case: camel
          string_interpolation: double_braces
          input_directory: lib/core/i18n
          namespaces: true
          output_format: multiple_files
          output_file_name: strings.g.dart
          output_directory: lib/core/i18n
          maps:
            - core.changeLanguage.languages

Thank you very much.

I think it would be good feature to have the possibility to not apply key_case to maps. Or select different casing for maps. Or select different casing for each map (but I would be happy with global maps setting).
I am using key_case: camel for all of my translations, because it's the Dart's language style.
My API returns JSON error response in format

{
    "code": "user_not_found",
    "reason": "User was not found."
}

and now I would like to use that code to lookup the translated reason message.
Something like

try {
  something();
} on ApiException catch (ex) {
  _notificationService.showError(t.apiCodes[ex.code]);
}

but since all keys are now camelCase, I would need to do my own recasing of API response codes to camelCase. Which is not a big deal but this feature would still be great :)

Hi,

I wonder if there is better way to add keys and rebuild project. My current setup with 6 languages is such:

1. add a key to strings.i18n.json manually
2. add same key into remaining nto strings_**.i18n.json (annoying and repetitive task)
3. run flutter pub run fast_i18n
4. finally I can use the string
5. rinse & repeat for next string

This is just too time consuming, because first, I cannot use string unless it's in all translation files, otherwise the project will not build. Second, running flutter run pub fast_i18n is again manual step - can this be automated with auto-reload?

Describe the bug

Using flutter pub build_runner build outputs nothing. If I make a change to my json file with my strings and check the generated file it has not been written to, nor does it contain a field for the new string/text. The output from build runner seems to confirm this.

$ flutter pub run build_runner build --delete-conflicting-outputs
[INFO] Generating build script...
[INFO] Generating build script completed, took 542ms

[INFO] Initializing inputs
[INFO] Reading cached asset graph...
[INFO] Reading cached asset graph completed, took 70ms

[INFO] Checking for updates since last build...
[INFO] Checking for updates since last build completed, took 373ms

[INFO] Running build...
[INFO] Running build completed, took 8ms

[INFO] Caching finalized dependency graph...
[INFO] Caching finalized dependency graph completed, took 37ms

[INFO] Succeeded after 60ms with 0 outputs (0 actions)

If I run fast_i18n "directly" with flutter pub run fast_i18n it works with the generated files updated with my new string keys.

My build.yaml looks like:

# yaml-language-server: $schema=https://json-schema.org/draft-07/schema#
targets:
  $default:
    builders:
      fast_i18n:
        options:
          base_locale: en
          namespaces: true
          fallback_strategy: base_locale
          input_directory: strings
          input_file_pattern: .i18n.json
          output_directory: lib/i18n
          output_format: multiple_files

Versions from my pubspec

  build_runner: ^2.1.7
  fast_i18n: ^5.11.0

To Reproduce
Steps to reproduce the behavior:

1. Use the build config above.
2. Run with flutter pub run fast_i18n and observe that files are generated correctly.
3. Make a change to the string file.
4. Run with flutter pub run build_runner build --delete-conflicting-outputs.
5. Observe that the files have not been updated

Expected behavior
Generate files both using the build runner and the fast_i18n task

Affected version: 5.6.0

Setting following in build.yaml does not seem to have effect on generated maps case:

      key_map_case: pascal
      flat_map: false
      maps:
        - ProjectActivityType
        - AddressBookType

1. When flat_map is false it does not generate any maps in strings.g.dart
2. Even when flat_map is enabled to true than the key_map_case case transformation is ignored.

JSON:

{
  "AddressBookType": {
    "COMPANY": "Company",
    "PERSON": "Person"
  }
}

will produce nin strings.g.dart:

AppLocale.cs: {
  'addressBookType.company': 'Firma',
  'addressBookType.person': 'Osoba',
}

Hello @Tienisto

For the translators it would be helpful to have some information like source keys count and word count.
Can you output this information to the console after the build process?

Thank you for the best localization plugin ✨

Hello,

my translation files are getting big very fast. I really like to have a json file for components, for services etc. split up and not in one file per language. I dont want to write my own service which merges multiple files into one to compile it with the runner afterwards.

Are you planning on introducing multiple file support per language?

Best regards

The app crashes with following error. I used string.cs_CZ.i18n.json file and also LocaleSettings.setLocaleRaw("cs_CZ");

I/flutter ( 5843): ════════
I/flutter ( 5843): Warning: This application's locale, cs_CZ, is not supported by all of its
I/flutter ( 5843): localization delegates.
I/flutter ( 5843): > A MaterialLocalizations delegate that supports the cs_CZ locale was not found.
I/flutter ( 5843): See https://flutter.dev/tutorials/internationalization/ for more
I/flutter ( 5843): information about configuring an app's locale, supportedLocales,
I/flutter ( 5843): and localizationsDelegates parameters.
I/flutter ( 5843): ════════
I/flutter ( 5843): 

======== Exception caught by widgets library =======================================================
The following assertion was thrown building AppBar(dirty, dependencies: [_LocalizationsScope-[GlobalKey#0dcea]], state: _AppBarState#471e0):
No MaterialLocalizations found.

AppBar widgets require MaterialLocalizations to be provided by a Localizations widget ancestor.
The material library uses Localizations to generate messages, labels, and abbreviations.

To introduce a MaterialLocalizations, either use a MaterialApp at the root of your application to include them automatically, or add a Localization widget with a MaterialLocalizations delegate.

The specific widget that could not find a MaterialLocalizations ancestor was: AppBar
  dirty
  dependencies: [_LocalizationsScope-[GlobalKey#0dcea]]
  state: _AppBarState#471e0
The ancestors of this widget were: 
  : Scaffold
    dependencies: [_InheritedTheme, MediaQuery, _EffectiveTickerMode, _LocalizationsScope-[GlobalKey#0dcea], Directionality, UnmanagedRestorationScope, _ScaffoldMessengerScope]
    state: ScaffoldState#1a26c(tickers: tracking 2 tickers)
  : MyHomePage
    dependencies: [MediaQuery]
    state: _MyHomePageState#24804
  : MaterialApp
    state: _MaterialAppState#c0250
  : MyApp
  : _InheritedLocaleData
  : TranslationProvider-[LabeledGlobalKey<_TranslationProviderState>#7e437]
    state: _TranslationProviderState#794d5
  ...
The relevant error-causing widget was: 

Describe the bug
Empty lists throw an error

To Reproduce
Generate the i18n file using this json:

{
  "title": "hi",
  "features": []
}

And add an interface:

targets:
  $default:
    builders:
      fast_i18n:
        options:
          interfaces:
            Test: test

Expected behavior
Should render a getter returning an empty list. E.g. List<String> features => [];

I am attaching the image of the hint:

Note: key_case is snake.
Example is key in json "toast_cycle_alert_30_min" and get method is named as "toast_cycle_alert_3_0_min"

I am attaching the image of the hint that lint reports for the generated file.

Motivation
If a different output directory than the input directory is defined, and any of these directories does not exist an error will be thrown.

Generating translations...

Found build.yaml in /Users/.../code/app/build.yaml

 -> fileType: json
 -> baseLocale: en
 -> fallbackStrategy: baseLocale
 -> inputDirectory: /Users/.../code/app/strings
 -> inputFilePattern: .i18n.json
 -> outputDirectory: /Users/.../code/app/lib/i18n
 -> outputFilePattern (deprecated): .g.dart
 -> outputFileName: null
 -> outputFileFormat: multipleFiles
 -> renderLocaleHandling: true
 -> namespaces: false
 -> translateVar: t
 -> enumName: AppLocale
 -> translationClassVisibility: private
 -> keyCase: null (no change)
 -> keyCase (for maps): null (no change)
 -> paramCase: null (no change)
 -> stringInterpolation: dart
 -> renderFlatMap: true
 -> renderTimestamp: true
 -> maps: []
 -> pluralization/auto: cardinal
 -> pluralization/cardinal: []
 -> pluralization/ordinal: []
 -> contexts: no custom contexts
 -> interfaces: no interfaces

Found base name: "strings" (used for output file name and class names)
Scanning translations...

   (base) en -> /Users/.../code/app/strings/strings.i18n.json
Unhandled exception:
FileSystemException: Cannot open file, path = '/Users/.../code/app/lib/i18n/strings.g.dart' (OS Error: No such file or directory, errno = 2)
#0      _File.throwIfError (dart:io/file_impl.dart:635:7)
#1      _File.openSync (dart:io/file_impl.dart:479:5)
#2      _File.writeAsBytesSync (dart:io/file_impl.dart:604:31)
#3      _File.writeAsStringSync (dart:io/file_impl.dart:628:5)
#4      generateTranslations (file:///Users/.../flutter/.pub-cache/hosted/pub.dartlang.org/fast_i18n-5.10.0/bin/fast_i18n.dart:341:10)
<asynchronous suspension>
#5      main (file:///Users/.../flutter/.pub-cache/hosted/pub.dartlang.org/fast_i18n-5.10.0/bin/fast_i18n.dart:47:5)
<asynchronous suspension>
pub finished with exit code 255

There should either be a more descriptive error, or the ability to create the intermediate output directories (in this case the i18n directory inside lib).

Developer Experience
A field in build.yaml can control if directories should be turned on

I am attaching the image of the hint that lint reports for the generated file.

This is an idea for the next feature introducing custom contexts.

Motivation
There should be an option to differentiate between male and female forms. It should be generic so we can add more use cases.

Developer Experience
Similar to pluralization, there should be an additional parameter. Here it will be context.

{
  "welcome": {
    "male": "Mr $name",
    "female": "Ms $name"
  }
}

String a = t.welcome(name: 'Tom', context: GenderContext.male);

The enum should be configurable. There can be more than one context type.

targets:
  $default:
    builders:
      fast_i18n:i18nBuilder:
        options:
          contexts:
            gender_context:  # The resulting enum will be in pascal case, i.e. "GenderContext"
              enum:
                - male
                - female
              auto: false
              paths:
                - welcome
            polite_context:  # Imaginary context type called "PoliteContext"
              enum:
                - polite
                - neutral
                - rude
              auto: on

Some languages may have fewer context types, therefore we may collapse them:

{
  "welcome": {
    "male,female": "$name"
  }
}

Not sure if this code should be removed but please check. I am attaching the image:

Currently, only linked translations are supported which do not accept any parameters.

This is how it should look like, when parameters are supported:

{
    "myName": "my name is $name",
    "myAge": "I am $age years old",
    "introduce": "Hello, @:myName and @:myAge"
}

Combine the parameters.

String s = t.introduce(name: 'Tom', age: 27); // Hello, my name is Tom and I am 27 years old.