Infer Slack Bolt TypeScript types

Hello, after upgrading to Slack bolt "@slack/bolt": "^3.3.0",, i am getting this TypeScript errors for types not existing.

Was trying to dig deep into Slack Bolt framework to figure out the types but to no avail so far.

Any help would be much appreciated. Thanks in advance.

 export const isThreadReply = (): Middleware<SlackEventMiddlewareArgs<'message'>> => {
  return async ({ event, next }): Promise<void> => {
    if (event.thread_ts && next) {
      await next();
    }
  };
};

Property 'thread_ts' does not exist on type 'KnownEventFromType<"message">'. Property 'thread_ts' does not exist on type 'EKMAccessDeniedMessageEvent'.ts(2339)

export const isParentMessageFromBot = (): Middleware<SlackEventMiddlewareArgs<'message'>> => {
  return async ({ context, message, next }): Promise<void> => {
    if (context.botUserId === message.parent_user_id && next) {
      await next();
    }
  };
};

Property 'parent_user_id' does not exist on type 'KnownEventFromType<"message">'. Property 'parent_user_id' does not exist on type 'BotMessageEvent'.ts(2339)

export const isNotBotMessage = (): Middleware<SlackEventMiddlewareArgs<'message'>> => {
return async ({ event, next }): Promise<void> => {
  if (!event.bot_profile && next) {
    await next();
  }
};
};

Property 'bot_profile' does not exist on type 'KnownEventFromType<"message">'. Property 'bot_profile' does not exist on type 'GenericMessageEvent'.ts(2339)

[seratch]

@erkand-imeri Can you upgrade the bolt version to the latest v3.4.0, which was just released? It should work with the version (the reason why bot_profile exists is that I added by #957 and the change is included in v.3.4.0)

[seratch]

@erkand-imeri Thanks for flagging this.

Unfortunately, the pull request https://github.com/slackapi/bolt-js/pull/709 (included in v2.6.0) changed the behavior around message events. The change is good for safer typing, but it became more confusing for users. I’m going to improve this at https://github.com/slackapi/bolt-js/issues/904 in the near future.

For this moment, if/else statements can help the TypeScript compiler understand which type should be chosen from the union type MessageEvent.

For instance, the following code compiles as event.subtype === undefined helps TS compiler determine the type of event as GenericMessageEvent.

export const isThreadReply = (): Middleware<SlackEventMiddlewareArgs<'message'>> => {
  return async ({ event, next }): Promise<void> => {
    if (event.subtype === undefined && event.thread_ts && next) {
      await next();
    }
  };
};

Similarly, the following works for the second example:

export const isParentMessageFromBot = (): Middleware<SlackEventMiddlewareArgs<'message'>> => {
  return async ({ context, message, next }): Promise<void> => {
    if (message.subtype === undefined && context.botUserId === message.parent_user_id && next) {
      await next();
    }
  };
};

But I found that even the latest revision does not work with the last example. I will include a fix for this in the next version, which we will release shortly.

Again, we’ll improve this issue at https://github.com/slackapi/bolt-js/issues/904. v3.5 or later should be working better for you. I do understand this type of error is frustrating when you use TypeScript. It’d be appreciated if you could understand the current situation around this project.