This is a simple framework to demonstrate a problem that I am having with accessing assets from other packages.
The project uses the 'melos' package (which can be installed from pub.dev using dart pub global activate melos) to manage a monorepo which contains
- 2 apps
- 1 library/package that is common to the 2 apps.
With this structure, the apps are able access the classes that are defined/exported by the shared library/package.
Unfortunately, there is an issue with the shared assets, specifically the JSON files that contain the language translations.
When either of the apps are launched, they cause an exception in flutter/services/asset_bundle.dart
E/flutter (25659): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: Unable to load asset: lang/en.json
It appears that the assets are not being built into the rootBundle (if you set a breakpoint on line #24 in app_localizations.dart, rootBundle shows as empty).
After much experimentation and further searching, I located flutter/flutter#65921. This flutter issue clarifies that the lookup string provided to rootBundle must include the full package path to the assets. You cannot use the abbreviated form that is currently (as of 06/2021) indicated in the flutter documentation.
So in app_localizations.dart changing from:
String jsonString = await rootBundle.loadString('lang/${locale.languageCode}.json');
to
String jsonString = await rootBundle.loadString('packages/flight_translations_library/lang/${locale.languageCode}.json');
solved the problem.