Avoid BuildContext Extensions

newdart

Avoid using BuildContext extensions to access Bloc or Cubit instances.

Rationale

For consistency and for the sake of being explicit, prefer directly using the underlying methods instead of BuildContext extensions. This is also beneficial for testing because it is not possible to mock an extension method.

| extension | explicit method | | ---------------- | ------------------------------------------------------------------- | | context.read | BlocProvider.of<Bloc>(context, listen: false) | | context.watch | BlocBuilder<Bloc, State>(...) or BlocProvider.of<Bloc>(context) | | context.select | BlocSelector<Bloc, State>(...) |

Examples

Avoid using BuildContext extensions to interact with Bloc or Cubit instances.

BAD:

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

class CounterPage extends StatelessWidget {
  const CounterPage({super.key});

  @override
  Widget build(BuildContext context) {
    final count = context.watch<CounterBloc>().state;

    return Column(
      children: [
        Text('Count: $count'),
        ElevatedButton(
          onPressed: () {
            context.read<CounterBloc>().add(CounterIncrement());
          },
          child: const Text('Increment'),
        ),
      ],
    );
  }
}

GOOD:

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

class CounterPage extends StatelessWidget {
  const CounterPage({super.key});

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        BlocBuilder<CounterBloc, int>(
          builder: (context, state) => Text('Count: $state'),
        ),
        ElevatedButton(
          onPressed: () {
            BlocProvider.of<CounterBloc>(context).add(CounterIncrement());
          },
          child: const Text('Increment'),
        ),
      ],
    );
  }
}

Enable

To enable the avoid_build_context_extensions rule, add it to your analysis_options.yaml under bloc > rules:

YAML List
YAML Map

bloc:
  rules:
    - avoid_build_context_extensions