Flutter localization with ARB files

What an ARB file holds

An ARB file is JSON. Plain keys are messages. A key starting with @ holds metadata for the message of the same name, such as a description for translators. @@locale names the language of the file.

LocalizeMe writes @@locale on every export and turns each key's description into its @key block, so translator notes survive the round trip.

{
  "@@locale": "de",
  "checkoutPayButton": "Jetzt bezahlen",
  "@checkoutPayButton": {
    "description": "Primary button on the checkout screen"
  }
}

Setting up gen-l10n

Point l10n.yaml at the folder with your ARB files and name the template file. Flutter generates AppLocalizations from it on the next build.

arb-dir: lib/l10n
template-arb-file: app_en.arb
output-localization-file: app_localizations.dart

Plurals in ARB files

Flutter expresses plurals as ICU messages inside one value. LocalizeMe stores plurals as one key per form instead, and reads camel-case plural keys such as itemCountOne and itemCountOther from an imported ARB file. The ARB export writes each form as its own key today, not as an ICU message, so plural messages need a template you maintain in code for now.

Keeping ARB files out of merge conflicts

Pull the ARB files before running flutter gen-l10n, and translators never touch the repository.

localizeme init --project 42 --format arb --path 'lib/l10n/app_{locale}.arb'
localizeme pull
flutter gen-l10n

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