flappy_translator

A Flutter internationalized strings generator which automatically imports localization strings from a CSV file.

This is especially useful as any team member can work on a CSV file, with the translations imported into the project with the use of a simple terminal command. This contrasts starkly to the default i18n approach in which dart files need to be manually for new keys and languages.

Getting Started

In order to use the flappy_translator package, please provide your translations in a CSV file - separators , and ; have been tested to work.

Create a CSV file

Consider that we have a table of localizations for the following languages:

keysfrenesde_CH
appTitleMa super applicationMy awesome applicationMi gran applicationMeine tolle App
subtitleUn sous titreA subtitleUn subtitulòEin Untertitel
descriptionUn texte avec une variable : %1$sText with a variable: %1$sUn texto con una variable : %1$sText mit einer Variable: %1$s
littleTest"Voici, pour l'exemple, ""un test"" avec la variable %age$d""Here is, for the example, ""a test"" with the variable %age$d""Aqui esta, por ejemplo, ""una prueba"" con la variable %age$d""Hier ist, zum Beispiel, ""ein Test"" mit der Variable %age$d"

This spreadsheet would be exported as the following CSV file:

keys,fr,en,es,de_CH
appTitle,Ma super application,My awesome application,Mi gran application,Meine tolle App
subtitle,Un sous titre,A subtitle,Un subtitulò,Ein Untertitle
description,Un texte avec une variable : %1$s,Text with a variable: %1$s,Un texto con una variable : %1$s,Text mit einer Variable: %1$s
littleTest,"Voici, pour l'exemple, ""un test"" avec la variable %age$d","Here is, for the example, ""a test"" with the variable %age$d","Aqui esta, por ejemplo, ""una prueba"" con la variable %age$d","Hier ist, zum Beispiel, ""ein Test"" mit der Variable %age$d"

Add dependency

dependencies:
  flutter_localizations:
    sdk: flutter
    
dev_dependencies: 
  flappy_translator: 

Define Settings

Settings for flappy_translator can be optionally set in your project's pubspec.yaml file:

flappy_translator:
  input_file_path: "test.csv"
  output_dir: "lib"
  file_name: "i18n"
  class_name: "I18n"
  delimiter: ","
  start_index: 1
  depend_on_context: true
  use_single_quotes: false
  replace_no_break_spaces: false
SettingDefaultDescription
input_file_pathN/AA path to the input CSV file.
output_dirlibA directory to generate the output file.
file_namei18nA filename for the generated file.
class_nameI18nA class name for the generated file.
delimiter,A delimited to separate columns in the input CSV file.
start_index1The column index where translations begin (i.e. column index of main language.)
depend_on_contexttrueWhether the generated localizations should depend on BuildContext
use_single_quotesfalseWhether the generated file should use single or double quotes for strings.
replace_no_break_spacesfalseWhether no break spaces (\u00A0) should be replaced with normal spaces (\u0020).

Run package

Make sure that your current working directory is the project root.

A file path to the CSV file must be supplied, either as a setting in pubspec.yaml or as a command line argument (CLA), while the output directory can also be optionally supplied as a CLA.

flutter pub get
flutter pub run flappy_translator <test.csv> <output dir>

Use the i18n generated file

The package used your CV file in order to generate a file named file_name in output_dir you provided. The following example uses the default class_name I18n with a dependency on BuildContext:

  1. Add the I18nDelegate to your delegates
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      localizationsDelegates: [
        const I18nDelegate(),
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
      ],
      supportedLocales: I18nDelegate.supportedLocals,
      home: Home(),
    );
  }
}
  1. Use your generated I18n class ! :)
class Home extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Center(
          child: Column(
            children: <Widget>[
              Text(I18n.of(context).appTitle),
              Text(I18n.of(context).description(var1: 2)),
              Text(I18n.of(context).littleTest(age: 32)),
            ],
          ),
        ),
      ),
    );
  }
}

Update iOS Info.plist

For iOS, ios/Runner/Info.plist needs to be updated with an array of the languages that the app supports:

<key>CFBundleLocalizations</key>
<array>
  <string>fr</string>
  <string>en</string>
  <string>es</string>
  <string>de</string>
</array>

For more information, see Internationalizing Flutter apps.

Rules and functionalities

Default language

The first language's column of your CSV file will be considered as the default one. That means :

  • If other languages does not have translation for specific words, it will take the corresponding one in the default language.

  • The first column must be totally filled ! It will not work otherwise.

Handling different languages for one country

You have the possibility, since version 1.4 to write something like de_CH. It will take the Swiss's German language.

Add variables in Strings

We added the possibility to handle variables in the Strings. This means respecting some rules :

  1. In order to be able to recognize them, you must write them this way :
  • %myVariable$d (d stands for an int type)
  • %myVariable$s (s stands for a String type)
  1. if your variable's name start with a number, the generated name will be varmyVariable Otherwise, the generated variable name would be the name you provided.
  • %1$d becomes var1
  • %age$d becomes age
  1. Variables are optional in the generated dart code

Let's take the example of the description String in the CSV we used.

The generated function signature will be :

String description({String var1,})

If the variables are not provided, the String will be given without replacing the variables placeholders.

Libraries

csv_parser
default_settings
file_parser
flappy_logger
flappy_translator
template

Dart

VM

dart:ffi
Foreign Function Interface for interoperability with the C programming language. [...]

Web

dart:html
HTML elements and other resources for web-based applications that need to interact with the browser and the DOM (Document Object Model). [...]
dart:js
Low-level support for interoperating with JavaScript. [...]
dart:js_util
Utility methods to efficiently manipulate typed JSInterop objects in cases where the name to call is not known at runtime. You should only use these methods when the same effect cannot be achieved with @JS annotations. These methods would be extension methods on JSObject if Dart supported extension methods.