The getter '{string_key}' was called on null.

[ammar-esrawi]

static S of(BuildContext context) => Localizations.of<S>(context, S); ,
this call returns null
so the usage like will produce the exception The getter '{string_key}' was called on null.

[long1eu]

I need more info.

[ammar-esrawi]

@long1eu
I think the problem comes from the flutter frame work it self
but in general the issue occur once you try to reach the S.of(context).SOMETHING inside a StateFull widget this will make the call return Localizations.of<S>(context, S); returns null instead of instance from S class

,i created another issue in the flutter repo it contains more details
please follow this

i am using this SDK

environment:
  sdk: ">=2.0.0-dev.68.0 <3.0.0"

[long1eu]

You didn't setup the plugin. You don't have the proper LocalisationDelegate into you app. Follow the instructions carefully. În joi, 10 ian. 2019, 19:35 ammar-esrawi <notifications@github.com a scris:

…

@long1eu <https://github.com/long1eu> I think the problem comes from the flutter frame work it self but in general the issue occur once you try to reach the S.of(context).SOMETHING inside a StateFull widget this will make the call return Localizations.of<S>(context, S); returns null instead of instance from S class ,i created another issue in the flutter repo it contains more details please follow this <flutter/flutter#26365> i am using this SDK environment: sdk: ">=2.0.0-dev.68.0 <3.0.0" — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#35 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AI2nVlDdfGBIWj3BLdbQds9c5ABH_nl4ks5vB3nhgaJpZM4Z4OhQ> .

[long1eu]

Feel free to reopen the issues if you have the same problem after following the instructions.

[ammar-esrawi]

i tested your sample app and it did not work for me
in your app you setup the delegates and supported locals but did not call the values, i cloned your app and only changed one line in the main.dart file

home: MyHomePage(title: S.of(context).app_name),

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      onGenerateTitle: (BuildContext context) => S.of(context).app_name,
      localizationsDelegates: const <LocalizationsDelegate<WidgetsLocalizations>>[
        S.delegate,
      ],
      supportedLocales: S.delegate.supportedLocales,
      localeResolutionCallback:
          S.delegate.resolution(fallback: const Locale('en', '')),
      localeListResolutionCallback:
          S.delegate.listResolution(fallback: const Locale('en', '')),
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: S.of(context).app_name),
    );
  }
}

this generated the following log

Initializing hot reload...
Syncing files to device Android SDK built for x86...
I/flutter ( 3688): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 3688): The following NoSuchMethodError was thrown building MyApp(dirty):
I/flutter ( 3688): The getter 'app_name' was called on null.
I/flutter ( 3688): Receiver: null
I/flutter ( 3688): Tried calling: app_name
I/flutter ( 3688): 
I/flutter ( 3688): When the exception was thrown, this was the stack:
I/flutter ( 3688): #0      Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:50:5)
I/flutter ( 3688): #1      MyApp.build (package:test_app/main.dart:23:45)
I/flutter ( 3688): #2      StatelessElement.build (package:flutter/src/widgets/framework.dart:3774:28)
I/flutter ( 3688): #3      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3721:15)
I/flutter ( 3688): #4      Element.rebuild (package:flutter/src/widgets/framework.dart:3547:5)
I/flutter ( 3688): #5      BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2286:33)
I/flutter ( 3688): #6      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:676:20)
I/flutter ( 3688): #7      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5)
I/flutter ( 3688): #8      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter ( 3688): #9      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter ( 3688): #10     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:751:7)
I/flutter ( 3688): #12     _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter ( 3688): #13     _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter ( 3688): #14     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter ( 3688): (elided one frame from package dart:async)
I/flutter ( 3688): ════════════════════════════════════════════════════════════════════════════════════════════════════
Reloaded 1 of 420 libraries in 1,341ms.
 

note :
i can not reopen the issue

Thank you for the very useful plugin

[ammar-esrawi]

dart versaion

flutter version

[long1eu]

Your you can't use S with that context. S.of(context) will always return null.

[long1eu]

try it like this

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      onGenerateTitle: (BuildContext context) => S.of(context).app_name,
      localizationsDelegates: const <LocalizationsDelegate<WidgetsLocalizations>>[
        S.delegate,
      ],
      supportedLocales: S.delegate.supportedLocales,
      localeResolutionCallback: S.delegate.resolution(fallback: const Locale('en', '')),
      localeListResolutionCallback: S.delegate.listResolution(fallback: const Locale('en', '')),
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Builder(
        builder: (BuildContext context) {
          return MyHomePage(title: S.of(context).app_name);
        },
      ),
    );
  }
}

[ammar-esrawi]

try it like this

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      onGenerateTitle: (BuildContext context) => S.of(context).app_name,
      localizationsDelegates: const <LocalizationsDelegate<WidgetsLocalizations>>[
        S.delegate,
      ],
      supportedLocales: S.delegate.supportedLocales,
      localeResolutionCallback: S.delegate.resolution(fallback: const Locale('en', '')),
      localeListResolutionCallback: S.delegate.listResolution(fallback: const Locale('en', '')),
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Builder(
        builder: (BuildContext context) {
          return MyHomePage(title: S.of(context).app_name);
        },
      ),
    );
  }
}

this worked fine thank you

[long1eu]

Do you understand why? În mar., 15 ian. 2019, 00:04 ammar-esrawi <notifications@github.com a scris:

…

try it like this class MyApp extends StatelessWidget { @OverRide Widget build(BuildContext context) { return MaterialApp( title: 'Flutter Demo', onGenerateTitle: (BuildContext context) => S.of(context).app_name, localizationsDelegates: const <LocalizationsDelegate<WidgetsLocalizations>>[ S.delegate, ], supportedLocales: S.delegate.supportedLocales, localeResolutionCallback: S.delegate.resolution(fallback: const Locale('en', '')), localeListResolutionCallback: S.delegate.listResolution(fallback: const Locale('en', '')), theme: ThemeData( primarySwatch: Colors.blue, ), home: Builder( builder: (BuildContext context) { return MyHomePage(title: S.of(context).app_name); }, ), ); } } this worked fine thank you — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#35 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AI2nVvMCjhg3pQtuAu5ymZQsPvU6lkBnks5vDP7WgaJpZM4Z4OhQ> .

[ammar-esrawi]

Yep i have been using the widget context since your generated Class S deppend on Localizations which only work in Material context so it worked through the builder

I think these information need to be documented in Flutter website cuz i read the documents but this important info were not presented

I appreciate your efforts

Also i wish if you can work on a plugin for the toJson ,fromJson also, they are annoying issue

[long1eu]

try https://pub.dartlang.org/packages/built_value

[po1arbear]

delete the 'generated' package, then it will recreate automatic ,solved my problem

[ahmedGibran]

Isolate the user interface from the main application and it will work for you.