Getting BuildContext in Flutter for localization - dart

Question

I try to localize a String in Flutter with the localization package. The problem is the location where my translation is needed. It is not related to the UI, rather it is somewhere deep in my model, where I don't have access to a BuildContext. Is there any other possibility to still make use of the translation function?
// I don't have a context variable here
MyLocalizations.of(context).trans("foo")

Answer 1

Yes there is. You don't need BuildContext to access strings. Here is my solution:
class Strings {
Strings._(Locale locale) : _localeName = locale.toString() {
current = this;
}
final String _localeName;
static Strings current;
static Future<Strings> load(Locale locale) async {
await initializeMessages(locale.toString());
final result = Strings._(locale);
return result;
}
static Strings of(BuildContext context) {
return Localizations.of<Strings>(context, Strings);
}
String get title {
return Intl.message(
'Hello World',
name: 'title',
desc: 'Title for the Demo application',
);
}
}
Future<Null> main() async {
final Locale myLocale = Locale(window.locale);
await Strings.load(myLocale);
runApp(MyApplication());
}
Now you can reference a string as follows:
final title = Strings.current.title;

Answer 2

I know this question is dated way back. But I came across this issue when implementing my application, and I dont see any "nice" way to handle it.
So here is my approach
class LanguageService {
static String defaultLanguage = 'en';
static Map<String, Map<String, String>> _localizedValues = {
'en': {
'title': 'Storefront',
'language': 'Language',
'googleLogin': 'Login with Google'
},
'vn': {
'title': 'Cửa hàng',
'language': 'Ngôn ngữ',
'googleLogin': 'Đăng Nhập với Google'
}
};
static set language(String lang) {
defaultLanguage = lang;
}
static String get title {
return _localizedValues[defaultLanguage]['title'];
}
static String get language {
return _localizedValues[defaultLanguage]['language'];
}
static String get googleLogin {
return _localizedValues[defaultLanguage]['googleLogin'];
}
}
Now you can reference a string as follows:
String title = LanguageService.title;
You can find the detailed tutorial here

Answer 3

AppLocalitzations needs the context.
You can create a class (e.g., Localization) to encapsulate AppLocalizations initialization and initialize it from the home widget using its context. After, can be used with a mixin:
import 'package:flutter/widgets.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';
class Localization {
static AppLocalizations _loc;
AppLocalizations get loc => Localization._loc;
static void init(BuildContext context) => _loc = AppLocalizations.of(context);
}
In the home widget:
...
#override
Widget build(BuildContext context) {
Localization.init(context);
return Scaffold(
...
Access to loc in some class (it isn't necessary to be a Widget) using mixins:
class XXXWidget extends StatelessWidget with Localization {
...
Text(loc.xxxx)
...
}
class _XXXXWidgetState extends State<XXXWidget> with Localization {
...
Text(loc.xxxx)
...
}
class XXXXController with Localization {
...
cardNumberValidator = RequiredValidator(errorText: loc.commons_Required);
...
}
Null safety version:
class Localization {
static AppLocalizations? _l;
AppLocalizations get loc => Localization._l!;
static void init(BuildContext context) => _l = AppLocalizations.of(context)!;
}

Answer 4

No, there is no other way because it is stored using an InheritedWidget, which is a part of the build tree and thus can only be accessed with a reference to it (the BuildContext).
You will need to pass your context to somewhere deep in your model.

Answer 5

I am not sure if i did it right (from performance point of view) and maybe someone can comment on this but i have rx BehaviorSubject in my AppLocalization and fire event once new locales are loaded. I am listening to it in my main.dart and doing setState on receiving an event.
I checked performance tab but did not noticed any big changes in it once comparing my method vs accessing translations through context (inherited widget).