code-generation

name	code-generation
description	Runs build_runner across core, data_source, and apps/main via the makefile after edits to freezed/injectable/retrofit/hive sources
license	MIT
compatibility	all
metadata	{"audience":"flutter-developers","framework":"flutter","pattern":"code-generation"}

Code Generation Skill

When to use

After editing any file annotated with @freezed, @JsonSerializable/@JsonKey, @Injectable/@LazySingleton/@Singleton/@module, @RestApi, @HiveType, or that declares a _StateData for a bloc.

Commands

The makefile is the canonical interface. It auto-detects fvm if present and falls back to the system Flutter SDK.

Command	What it runs
make gen_all	gen_core → gen_data_source → gen_main (full graph)
make gen_main	build_runner build only inside apps/main/
make gen_core	build_runner build only inside core/
make gen_data_source	build_runner build only inside modules/data_source/
make gen	Interactive picker for the same targets
make lang	Regenerates app_localizations_*.dart from localizations.csv
make asset	Regenerates the asset accessor under each package
make format	dart format . across the repo
make pub_get	pub get across plugins, core, main

When you don't know the scope of your change, run make gen_all. It's slower but never wrong.

Generated files

Pattern	Producer	Hand-edit?
*.freezed.dart	freezed	Never
*.g.dart	json_serializable, retrofit, hive_ce	Never
*.config.dart	injectable	Never
app_localizations*.dart	flutter intl tooling via make lang	Never

All generated files are committed to source control — CI does not regenerate them.

When generation fails

1. Stale cache — dart run build_runner clean from inside the failing package, then re-run make gen_<scope>.
2. Missing part directive — every freezed/json/retrofit source needs the matching part 'foo.freezed.dart'; / part 'foo.g.dart';.
3. Missing sealed — freezed unions and the bloc _StateData require sealed class.
4. Missing @Default(...) — non-nullable fields without a default break codegen.
5. Conflicting outputs — the makefile already passes --delete-conflicting-outputs; if you're invoking dart run build_runner directly, do the same.

Watch mode

Useful while iterating on a single package:

cd apps/main
fvm dart run build_runner watch --delete-conflicting-outputs   # or `dart run …` if no fvm

Stop with Ctrl-C. Don't leave it running in CI.

CI hook

For a pre-commit/CI gate, run make gen_all and then assert that no generated artifacts changed:

make gen_all
git diff --exit-code -- '**/*.freezed.dart' '**/*.g.dart' '**/*.config.dart' \
  'apps/main/lib/l10n/generated/**'

Checklist

• After adding/changing a @freezed/@Injectable/@RestApi/@HiveType source, make gen_all (or the narrow target) was run.
• After editing localizations.csv, make lang was run.
• No hand-edited generated files in the diff.
• All generated files are staged for commit.

Common mistakes

• Running dart run build_runner build without --delete-conflicting-outputs and stopping at the first conflict.
• Editing *.freezed.dart to silence an analyzer warning — fix the source instead.
• Forgetting that make gen_main does not touch core/ or modules/data_source/. When core types change, run make gen_all.

Related

• bloc-pattern
• data-layer
• module-scaffold