extension-action

name	extension-action
description	Extracts screen handlers and bloc listeners into a part-of "*.action.dart" extension file
license	MIT
compatibility	all
metadata	{"audience":"flutter-developers","framework":"flutter","pattern":"extension-action"}

Extension Action Skill

When to use

• A screen file has grown past ~100 lines mixing UI + handlers.
• You need to add _blocListener, onRefresh, navigation handlers, or form callbacks to an existing screen.
• Generator output is the canonical shape — every generated module already comes with this split.

File pair

<feature>_screen.dart   // UI + state controllers + part 'feature.action.dart';
<feature>.action.dart   // part of '<feature>_screen.dart';
                        // extension on _<Feature>ScreenState { ... }

feature.action.dart (note: dot, not underscore — matches generator output) is one library with the screen, so it can call private members of _<Feature>ScreenState.

Reference

<feature>_screen.dart:

import 'package:core/core.dart';
import 'package:flutter/material.dart';

import '../../../../l10n/localization_ext.dart';
import '../../../base/base.dart';
import '../bloc/<feature>_bloc.dart';

part '<feature>.action.dart';

class FeatureScreen extends StatefulWidget {
  static String routeName = '/feature';
  const FeatureScreen({super.key, this.args});

  final FeatureArgs? args;

  @override
  State<FeatureScreen> createState() => _FeatureScreenState();
}

class _FeatureScreenState extends StateBase<FeatureScreen> {
  final _refreshController = RefreshController(initialRefresh: true);

  @override
  FeatureBloc get bloc => BlocProvider.of(context);

  late ThemeData _themeData;
  TextTheme get textTheme => _themeData.textTheme;

  @override
  Widget build(BuildContext context) {
    _themeData = context.theme;

    return BlocListener<FeatureBloc, FeatureState>(
      listener: _blocListener,
      child: ScreenForm(
        title: l10n.featureTitle,
        child: SmartRefresher(
          controller: _refreshController,
          onRefresh: onRefresh,
          child: const FeatureBody(),
        ),
      ),
    );
  }
}

<feature>.action.dart:

part of '<feature>_screen.dart';

extension on _FeatureScreenState {
  void _blocListener(BuildContext context, FeatureState state) {
    hideLoading();
    _refreshController.refreshCompleted();
  }

  void onRefresh() {
    final id = widget.args?.id ?? widget.args?.initial?.id;
    if (id != null) {
      bloc.add(GetFeatureEvent(id));
    }
  }
}

What goes where

Action file (extension):

• _blocListener(BuildContext, State) — side effects from state changes (hide loading, complete refresh, show dialog/snackbar, navigate).
• onRefresh, onLoadMore, onSubmit — handlers passed to widgets.
• Form validation that dispatches events.
• Coordinator calls (context.goToX(...)).

Screen file:

• build, sub-Widget _buildX() helpers.
• initState / dispose.
• TextEditingController, GlobalKey, RefreshController declarations.
• bloc getter override.

Conventions

• Extension is anonymous (extension on _FeatureScreenState) in generated code; if you prefer a name, use <Feature>Action for greppability.
• Methods can be public (onRefresh) when the screen passes them as callbacks, or private (_handleX) when only used inside the action file.
• The part of line MUST be the first non-comment line of the action file.

Checklist

• part 'feature.action.dart'; (note: dot) directive in <feature>_screen.dart.
• part of '<feature>_screen.dart'; is the first line of the action file.
• _blocListener calls hideLoading() early so the screen-level loading delegate is unstuck on every state change.
• No widget build logic in the action file.
• No coordinator/context.goToX calls inside build — keep them in the action file.

Related

• bloc-pattern
• module-scaffold
• route-config