SnackBar with Riverpod

main.dart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
// ...
ref.listen(
  snackBarProvider,
  (previous, next) {
    if (mounted && next != null) {
      ScaffoldMessenger.of(context).showSnackBar(next);
    }
  },
  onError: (error, stackTrace) {
    // TODO implement
  },
);
// ...

snack_bar_provider.dart

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

final snackBarProvider =
    StateNotifierProvider<SnackBarNotifier, SnackBar?>((ref) {
  return SnackBarNotifier();
});

class SnackBarNotifier extends StateNotifier<SnackBar?> {
  SnackBarNotifier() : super(null);
  setSnackBar(SnackBar snackBar) {
    state = snackBar;
  }
}

sub.dart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
// ...
ref.read(snackBarProvider.notifier).setSnackBar(
  SnackBar(content: Text('Hello, world!')),
);
// ...