NestJS Slack Listeners and Handlers

🥰 Any kinds of contributions are welcome! 🥰

---

Features

• Class decorator @SlackEventListener
  • Decorate the class to use it as a Slack event listener, just like decorating HTTP listeners with @Controller.
• Method decorator @SlackEventHandler
  • Decorate the method to use it as a Slack event handler, just like decorating HTTP handlers with @Get, @Post, etc.
  • You can filter events by event type, or your custom filtering function.
• Slack Web API Client
  • Inject the Slack Web API client to your service class with @InjectSlackClient decorator.
  • You can use the client to send messages to Slack, or whatever you want to do.

Installation

yarn add nestjs-slack-listener

Usage

Please refer to the example for more details.

Settings

Import SlackModule

Import the module at your app module.

@Module({
  imports: [
    ConfigModule.forRoot({ isGlobal: true }),
    SlackModule.forRootAsync({
      useFactory: async (config: ConfigService<EnvVars>) => ({
        botToken: config.get('SLACK_BOT_TOKEN'),
      }),
      inject: [ConfigService],
    }),
  ],
  controllers: [AppController],
  providers: [],
})
export class AppModule {}

Event and Interactivity Subscription

You need to set event and interactivity subscriptions URL of your slack app so that the app can receive events and interactivity from slack.

• Event subscription
  • https://api.slack.com/apps/your-app-id/event-subscriptions
  • http://<hostname>/slack/events
• Interactivity subscription
  • https://api.slack.com/apps/your-app-id/interactive-messages
  • http://<hostname>/slack/interactivity

Decorators

Slack Event

Decorate the controller to use it as slack event listener.

@Controller('on-boarding')
@SlackEventListener()
export class OnBoardingController {}

Decorate the method of the controller to use it as slack event handler.

@Controller('on-boarding')
@SlackEventListener()
export class OnBoardingController {
  constructor(private readonly onboardingService: OnBoardingService) {}

  @SlackEventHandler('team_join')
  async onTeamJoin({ event: { user } }: IncomingSlackEvent<TeamJoinEvent>) {
    this.onboardingService.startOnBoarding({ user });
  }
}

Slack Interactivity

You can also decorate the listeners and handlers for slack-interactivity.

@Controller('on-boarding')
@SlackEventListener()
@SlackInteractivityListener()
export class OnBoardingController {
  constructor(private readonly onboardingService: OnBoardingService) {}

  @SlackEventHandler('team_join')
  async onTeamJoin({ event: { user } }: IncomingSlackEvent<TeamJoinEvent>) {
    this.onboardingService.startOnBoarding({ user });
  }

  @SlackInteractivityHandler(ACTION_ID.COMPLETE_QUEST)
  async completeOnBoarding({
    user: { id: userSlackId },
    actions: [{ value }],
  }: IncomingSlackInteractivity) {
    return this.onboardingService.completeOnBoarding({ userSlackId, value });
  }
}

Filters

Filter the events with function argument filter and string argument eventType of the decorator SlackEventHandler.

@Controller('memo')
@SlackEventListener()
export class MemoController {
  constructor(private readonly memoService: MemoService) {}

  @SlackEventHandler({
    eventType: 'message',
    filter: ({ event }) => event.text.includes('write this down!'),
  })
  async takeMemo({ event: { message } }: IncomingSlackEvent<MessageEvent>) {
    this.memoService.takeMemo({ message });
  }
}

You can also filter the events at the decorator SlackEventListener

@Controller('memo')
@SlackEventListener(({ event }) => event.channel === MEMO_CHANNEL)
export class OnBoardingController {
  constructor(private readonly memoService: MemoService) {}

  @SlackEventHandler({
    eventType: 'message',
    filter: ({ event }) => event.text.includes('write this down!'),
  })
  async onTeamJoin({ event: { user } }: IncomingSlackEvent<MessageEvent>) {
    this.memoService.takeMemo({ message });
  }
}

Slack Client

Use InjectSlackClient to use the slack web api client.

@Injectable()
export class OnBoardingService {
  constructor(
    private readonly userRepository: UserRepository,
    @InjectSlackClient()
    private readonly slack: SlackClient,
  ) {}
  ...
}

The injected SlackClient is identical to the official Slack Web API Client

await this.slack.chat.postMessage({
  channel: user.id,
  text: 'Hi there! 👋🏻',
  blocks: [
    {
      type: 'header',
      text: {
        type: 'plain_text',
        text: 'Hi there! 👋🏻',
      },
    },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: `Hello! Nice to meet you, ${user.name}! I'm *hanch*, a slack bot that helps you with onboarding process.`,
      },
    },
  ],
});