Unable to access thread_ts in message_replied message event payloads

[SpencerKaiser]

Description

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• enhancement (feature request)
• question
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Bug Report

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Reproducible in:

package version: ^3.2.0

node version: ^14

Expected result:

thread_ts will be available for messages

Actual result:

Compiler error

Code

  bolt.message(subtype('message_replied'), ({ message }) => {
    console.log(message.thread_ts);
  })

Property 'thread_ts' does not exist on type 'MessageEvent'.

[seratch]

Hi @SpencerKaiser , I know this may be a bit confusing but you can access the value via message.message.thread_ts.

app.message("foo", async ({ message }) => {
  if (message.subtype === "message_replied") {
    message.message.thread_ts
  }
});

event arg works in the same way:

app.message("foo", async ({ event }) => {
  if (event.subtype === "message_replied") {
    event.message.thread_ts
  }
});

[SpencerKaiser]

@seratch thanks for the super quick response!!

I actually tried that earlier and had a similar problem... I know that value is there, but I can't seem to make any progress on getting it out safely:

types.ts

import { App, Middleware } from '@slack/bolt';

export type AppMiddlewareFunction<Args> = (app: App) => Middleware<Args>;

messageReplied.ts

export const messageReplied: AppMiddlewareFunction<SlackEventMiddlewareArgs<'message'>> = (app: App) => async ({
  message,
  event,
}) => {
  console.log(message.message);
  // Property 'message' does not exist on type 'MessageEvent'.
  // Property 'message' does not exist on type 'GenericMessageEvent'.
  
  console.log(message.thread_ts);
  // Property 'thread_ts' does not exist on type 'MessageEvent'.
  // Property 'thread_ts' does not exist on type 'EKMAccessDeniedMessageEvent'.

  console.log(event.message);
  // Property 'message' does not exist on type 'MessageEvent'.
  // Property 'message' does not exist on type 'GenericMessageEvent'.

  console.log(message.thread_ts);
  // Property 'thread_ts' does not exist on type 'MessageEvent'.
  // Property 'thread_ts' does not exist on type 'EKMAccessDeniedMessageEvent'.
};

I know that pattern might look a little strange, but it was the best thing my team and I could figure out to make the handlers easily testable (which they really are!!). Any idea what the issue is there?

[seratch]

@SpencerKaiser interestingly (it's a TypeScript compiler's magic), having if statement makes the value's type compatible with "message_replied" events.

[SpencerKaiser]

I think the issue on my end is that SlackEventMiddlewareArgs<'message'> is yielding MessageEvent which does't include the properties from MessageRepliedEvent 🙁

Are you (or is someone else from your team) a Types guru that might now what's going on there?

[seratch]

yielding MessageEvent which does't include the properties from MessageRepliedEvent

MessageEvent is not fully deterministic yet. The type is a union type for ten types: https://github.com/slackapi/bolt-js/blob/%40slack/bolt%403.2.0/src/types/events/message-events.ts#L3-L11

Thus, the type provides only the fields available for all the possible types. And then, once you tell the subtype is "message_replied` (by having if statement as above), the TS compiler can narrow it down. I know this sounds a bit tricky but this is how this library works.

If this library provides type parameter like the one for app.action: https://github.com/slackapi/bolt-js/blob/%40slack/bolt%403.2.0/src/App.ts#L477-L480

app.action({"action_id": "aid", "type": "block_actions"}, async ({ action, ack }) => {
  action // this is compatible with `block_actions` payload
});

The following code may work.

app.message({"pattern": "foo", "subtype": "message_replied"}, async ({ message }) => {
    message.message.thread_ts // this compiles
});

[SpencerKaiser]

Setting that subtype to message_replied yields a message of type never ☹️