json - 使用 json 文件中的动态字符串进行 flutter 国际化

Question

到目前为止，我使用的是动态字符串，如本文的解决方案所示:
Flutter internationalization - Dynamic strings

下面是一个例子:

AppLocalizations.of(context).userAge(18)

在 AppLocalizations.dart 上:

userAge(age) => Intl.message(
  "My age is $age",
  name: "userAge",
  args: [age]);
// Return "My age is 18"

但后来我读了这篇关于 flutter 国际化的文章: https://medium.com/flutter-community/flutter-internationalization-the-easy-way-using-provider-and-json-c47caa4212b2
其中显示了如何使用 json 文件作为字符串的资源文件进行本地化。它看起来更方便，所以我更喜欢使用这种方法，但不知道如何从具有动态值的 json 文件中获取字符串。

有什么解决办法吗？

Answer 1

要从 JSON 文件中获取具有动态值的字符串，您可以使用

final age = 18 //user input.
final ageString = 'user_age'
                   .localisedString()
                   .replaceAll(new RegExp(r'\${age}'), age)

en.json

{
  "user_age": "My age is ${age}",
  "user_name_age": "My name is ${name} and age is ${age}"
}

string_extension.dart

extension Localisation on String {
  String localisedString() {
    return stringBy(this) ?? '';
  }
}

另外，你可以做类似的事情，

  String localisedString(Map<String, String> args) {
      String str = localisedString();
      args.forEach((key, value) { 
        str = str.replaceAll(new RegExp(r'\${'+key+'}'), value);
      });
      return str;
  }
  
  //usecase
  final userName = 'Spider Man'
  final age = '18'
  final nameAgeString = 'user_name_age'.localisedString({'name': userName, 'age': age})

app_localisation.dart

Map<String, dynamic> _language;

String stringBy(String key) => _language[key] as String ?? 'null';

class AppLocalisationDelegate extends LocalizationsDelegate {
  const AppLocalisationDelegate();

  // override the following method if you want to specify the locale you are supporting.
  final _supportedLocale = ['en'];
  @override
  bool isSupported(Locale locale) => _supportedLocale.contains(locale.languageCode);

  @override
  Future load(Locale locale) async {
    String jsonString = await rootBundle
        .loadString("assets/strings/${locale.languageCode}.json");

    _language = jsonDecode(jsonString) as Map<String, dynamic>;
    print(_language.toString());
    return SynchronousFuture<AppLocalisationDelegate>(
        AppLocalisationDelegate());
  }

  @override
  bool shouldReload(AppLocalisationDelegate old) => false;
}