Flutter Google Sheet localizations generator

Generates a localizations delegate from an online Google Sheet file.


Add the following to your pubspec.yaml:

  flutter_sheet_localization: ^1.0.0

  flutter_sheet_localization_generator: ^1.0.0
  build_runner: ^1.3.1


1. Create a Google Sheet

Create a sheet with your translations (following the bellow format, an example sheet is available here) :


Make sure that your sheet is shared :


Extract from the link the DOCID and SHEETID values : https://docs.google.com/spreadsheets/d/<DOCID>/edit#gid=<SHEETID>) :

2. Declare a localization delegate

Declare the following AppLocalizationsDelegate class with the SheetLocalization annotation pointing to your sheet in a lib/localization.dart file :

import 'package:flutter/widgets.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter_sheet_localization/flutter_sheet_localization.dart';

part 'localization.g.dart';

@SheetLocalization("DOCID", "SHEETID", 1) // <- See 1. to get DOCID and SHEETID
// the `1` is the generated version. You must increment it each time you want to regenerate
// a new version of the labels.
class AppLocalizationsDelegate extends LocalizationsDelegate<AppLocalizations> {
  const AppLocalizationsDelegate();

  bool isSupported(Locale locale) =>
  Future<AppLocalizations> load(Locale locale) =>
  bool shouldReload(AppLocalizationsDelegate old) => false;

3. Generate your localizations

Run the following command to generate a lib/localization.g.dart file :

flutter packages pub run build_runner build

4. Configure your app

Update your Flutter app with your newly created delegate :

    locale: AppLocalizations.languages.keys.first, // <- Current locale
    localizationsDelegates: [
    const AppLocalizationsDelegate(), // <- Your custom delegate
        AppLocalizations.languages.keys.toList(), // <- Supported locales
    // ...

5. Display your labels

final labels = AppLocalizations.of(context);
print(labels.templated.hello(firstName: "World"));
print(labels.templated.contact(Gender.male, lastName: "John"));


Because of the caching system of the build_runner, it can't detect if there is a change on the distant sheet and it can't know if a new generation is needed.

The version parameter of the @SheetLocalization annotation solves this issue.

Each time you want to trigger a new generation, simply increment that version number and call the build runner again.

Google Sheet format

You can see an example sheet here.

Global format

The file should have :

  • A first header row
    • Column 0 : "Key"
    • then each supported language code ("en", "fr", ...)
  • Following rows for labels
    • Column 0 : the label key (can be a hierarchy, separated by dots)
    • then each translation based on language code of the column


It is pretty common to have variants of a label based on a condition (for example: Genders, Plurals, ...).

Simply duplicate your entries and end them with (<ConditionName>.<ConditionCase).

Example :


See example for more details.


The conditionals can be used the same way for plurals :

Example :


From your Dart code, you can then define a function :

Plural plural(int count) {
  if (count == 0) return Plural.zero;
  if (count == 1) return Plural.one;
  return Plural.multiple;

See example for more details.

Dynamic labels

You can insert a {{KEY}} template into a translation value to have dynamic labels.

A Dart function will be generated to be used from your code.

/// Sheet
values.hello, "Hello {{first_name}}!"

/// Code
print(labels.values.hello(firstName: "World"));

Typed parameters

You can also add one of the compatible types (int, double, num, DateTime) to the parameter by suffixing its key with :<type>.

/// Sheet
values.price, "The price is {{price:double}}\$"

/// Code
print(labels.values.price(price: 10.5));

Formatted parameters

You can indicate how the templated value must be formatted by ending the value with a formatting rule in brackets [<rule-key>]. This can be particulary useful for typed parameters.

The available formatting rules depend on the type and generally rely on the intl package.

Typerule-keyGenerated code
double, int, numdecimalPercentPattern, currency, simpleCurrency, compact, compactLong, compactSimpleCurrency, compactCurrency, decimalPattern, percentPattern, scientificPatternNumberFormat.<rule-key>(...)
DateTimeAny date format valid patternDateFormat('<rule-key>', ...).format(...)


/// Sheet
values.price, "Price : {{price:double[compactCurrency]}}"

/// Code
print(labels.values.price(price: 2.00));
/// Sheet
values.today, "Today : {{date:DateTime[EEE, M/d/y]}}"

/// Code
print(labels.values.today(date: DateTime.now()));

Why ?

I find the Flutter internationalization tools not really easy to use, and I wanted a simple tool for sharing translations. Most solutions also use string based keys, and I wanted to generate pure dart code to improve permormance.