Async configuration

Use forRootAsync() when the bot token or module options come from Nest configuration providers. It supports the standard useFactory, useClass and useExisting patterns.

useFactory

The factory may be synchronous or asynchronous and can inject dependencies:

TelegrafModule.forRootAsync({
  imports: [ConfigModule],
  useFactory: async (configService: ConfigService) => ({
    token: configService.getOrThrow<string>('TELEGRAM_BOT_TOKEN'),
  }),
  inject: [ConfigService],
});

useClass

Provide a class implementing TelegrafOptionsFactory when the option-building logic deserves its own provider:

TelegrafModule.forRootAsync({
  useClass: TelegrafConfigService,
});

@Injectable()
class TelegrafConfigService implements TelegrafOptionsFactory {
  createTelegrafOptions(): TelegrafModuleOptions {
    return {
      token: process.env.TELEGRAM_BOT_TOKEN!,
    };
  }
}

useExisting

To reuse a provider already registered by another module, use useExisting:

TelegrafModule.forRootAsync({
  imports: [ConfigModule],
  useExisting: TelegrafConfigService,
});

botName is available for all async registration styles. See multiple bots when registering more than one instance.