flutter-bloc（Flutter bloc 搜索）

BLoC Pattern

• Sealed States & Events: Always use sealed class for both States and Events to ensure exhaustive UI handling and compile-time safety.
• Immutability: All States, Events, and Domain Entities MUST be immutable (using final and Equatable or freezed).
• Official BLoC Part-Part Of Pattern: Every _bloc.dart file MUST include its corresponding _event.dart and _state.dart files using part directives. Each event/state file MUST have a part of directive pointing back to the bloc file. This ensures a single library scope and shared private members. // auth_bloc.dart part 'auth_event.dart'; part 'auth_state.dart'; class AuthBloc extends Bloc<AuthEvent, AuthState> {...} // auth_event.dart part of 'auth_bloc.dart'; // auth_state.dart part of 'auth_bloc.dart';
• Mandatory Directory Structure: Every BLoC feature set MUST reside in its own sub-directory within the bloc/ folder. Flat bloc/ directories are STRICTLY prohibited. presentation/bloc/ └── <bloc_name>/ ├── <bloc_name>_bloc.dart ├── <bloc_name>_event.dart └── <bloc_name>_state.dart
• Loading State Mandate: ALWAYS emit Loading before async work, then Success or Error. Never skip the loading state.
• Concurrency: Use transformers (e.g., restartable(), droppable()) for events requiring debouncing (search) or throttling (buttons).
• Zero-Logic UI: Widgets MUST NOT contain business logic, orchestration logic, or direct calls to external services. They should ONLY dispatch events and build UI based on BLoC states.

BLoC Widget Usage

• BlocBuilder for local UI rebuilds based on state
• BlocListener for side effects (navigation, snackbars, dialogs)
• BlocConsumer when both rebuild and side effects are needed
• context.read<Bloc>().add(Event()) for dispatching events
• context.watch<Bloc>().state for reactive rebuilds (inside build() only)

BLoC Submission Checklist

• Events and States use Equatable with correct props
• All async operations follow Loading → Success/Error pattern
• No business logic in UI widgets
• No SDK/API calls outside DataSources
• Zero hardcoded colors, spacing, or typography \u2014 use design tokens (AppColors, AppSpacing)
• Code formatted with dart format

Dependency Injection

• Use injectable for dependency injection and service location
• Standardized Injection:

- Use @injectable for screen-specific BLoCs to ensure a fresh instance per screen access. - Use @lazySingleton for global or shared BLoCs (e.g., AuthBloc, ThemeBloc, SettingsBloc, PasswordBloc).

• Organize blocs logically by feature and ensure strict separation of concerns

Navigation & Routing

• Dynamic Routes: STRICTLY prohibit hardcoded route strings in GoRouter configuration. Use static constants in AppRoutes.
• Centralized BLoCs: BLoC providers MUST be injected via ShellRoute or BlocProvider in app_router.dart when shared across multiple screens or within a feature branch.
• No Local Providers: Avoid BlocProvider in individual screen build() methods if the BLoC is needed by a feature set.
• Primitive Route Arguments: STRICTLY prohibit passing complex objects (BLoCs, ChangeNotifiers, Entity instances) as route arguments. Pass only primitive IDs/Keys and fetch data in the destination screen using Repository or Bloc injection.