🔔 Project 2: Error Notification System

Difficulty: Intermediate | Time: 30‑35 min

Objective

Build a notification module that listens to log records and sends alerts when a severe error occurs. Use the logging package and a simple email‑like console simulation.

Implementation

notifier.dart

import 'dart:io';
import 'package:logging/logging.dart';

class ErrorNotifier {
  final Logger logger;
  final List<String> adminEmails = ['admin@example.com'];

  ErrorNotifier({required this.logger}) {
    logger.onRecord.listen(_handleLogRecord);
  }

  void _handleLogRecord(LogRecord record) {
    if (record.level >= Level.SEVERE) {
      _sendNotification(record);
    }
  }

  void _sendNotification(LogRecord record) {
    for (var email in adminEmails) {
      // Simulate sending email
      print('📧 Sending alert to $email');
      print('   Subject: [SEVERE] ${record.loggerName}');
      print('   Message: ${record.message}');
      print('   Time: ${record.time}');
      // In real code, integrate with mailer package
    }
  }
}

Usage Example

void main() {
  final logger = Logger('my_app');
  logger.level = Level.ALL;

  // Attach notifier
  final notifier = ErrorNotifier(logger: logger);

  logger.severe('Database connection lost!');
  // Output:
  // 📧 Sending alert to admin@example.com
  //    Subject: [SEVERE] my_app
  //    Message: Database connection lost!
  //    Time: 2026-05-25 14:30:00.000
}

Test Your Project

Change the log level to WARNING and verify that only SEVERE and above trigger notifications.