Initialization Warm Up

Vaden includes a built-in initialization warm-up process to ensure critical startup tasks are completed before the server begins handling requests.

AppWarmup

To configure initialization tasks, you should now create a class like app_warmup.dart and define components that implement either:

• ApplicationRunner – runs when the application starts, regardless of arguments.
• CommandLineRunner – runs based on specific command-line arguments passed at startup.

Example:

import 'package:vaden/vaden.dart';

@Component()
class AppWarmup implements ApplicationRunner {
  @override
  Future<void> run(VadenApplication app) async {
    print('ApplicationRunner');
  }
}

@Component()
class AppRunner implements CommandLineRunner {
  @override
  Future<void> run(List<String> args) async {
    print('My args: $args');
  }
}

ApplicationRunner

• Runs automatically at application startup.
• Suitable for general initialization tasks like setting up services, running migrations, preparing caches, etc.

Example:

@Component()
class AppWarmup implements ApplicationRunner {
  @override
  Future<void> run(VadenApplication app) async {
    await prepareDatabase();
    initializeLogger();
  }
}

CommandLineRunner

• Runs based on the command-line arguments passed to the app.
• Allows conditional startup behavior based on the arguments.

Example:

@Component()
class AppRunner implements CommandLineRunner {
  @override
  Future<void> run(List<String> args) async {
    if (args.contains('migrate')) {
      await runMigrations();
    } else if (args.contains('seed')) {
      await seedDatabase();
    }
  }
}

Error Handling

• If any run method throws an exception, the error is printed and the server will not start.
• This ensures the application never runs in a partially initialized state.