chat_postMessage accepts thread_ts as a float but does not create a thread

[iyakushev]

Whenever a float timestamp is provided into the thread_ts of the chat_postMessage method slack returns {'ok': True, ... } in its response but no thread is created. The same message with a string as a timestamp will create a thread and post message as expected. I understand that the intended use is with a string. However, I find it strange that slackclient does not catch any type errors like this, or if it internally cast it to a string, something definitely goes wrong. Is that a correct response to a float correct?

Reproducible in:

Python 3.8.0
slackclient==2.9.1

Steps to reproduce:

...

rs = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="test msg")  # assume that it's Ok.
print(rs['ts'])  # "1602167511.000300"

# Correct usage
rs = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="thread test", thread_ts="1602167511.000300")
print(rs.data)  # this will show that response is Ok

# Bad timestamp
rs = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="thread test", thread_ts=1602167511.000300)
print(rs.data)  # this will show that response is Ok as well 

[mwbrooks]

Hey @nyanguy, thank you for the clearly explaining how you'd expect the SDK to handle a float and providing the steps to reproduce 🙏🏻

The Slack API on messages defines thread_ts as a string, so I'd expect you to receive an error if a float is used. I imagine a float fails because the trailing 0's on the decimal value are removed.

I'm going to mark this as a question that needs info and loop in our core maintainer:

@seratch can you shed some light on how you'd like to approach this issue? When a thread_ts is a float, should the SDK return an error, try to cast it as a string, or something else?

[seratch]

Thanks for writing in. I haven't been aware of this. I've verified the behavior with the following code snippet.

import logging
logging.basicConfig(level=logging.DEBUG)

channel = "#random"

import os
from slack import WebClient
client = WebClient(token=os.environ["SLACK_API_TOKEN"])
new_message = client.chat_postMessage(channel=channel, text="Hi!")
ts = new_message["ts"]
reply1 = client.chat_postMessage(channel=channel, text="What's up?", thread_ts=ts)
reply2 = client.chat_postMessage(channel=channel, text="What's up??", thread_ts=float(ts))
reply3 = client.chat_postMessage(channel=channel, text="What's up???", thread_ts=ts)

from slack.web.async_client import AsyncWebClient
async def main():
    client = AsyncWebClient(token=os.environ["SLACK_API_TOKEN"])
    new_message = await client.chat_postMessage(channel=channel, text="Hi!")
    ts = new_message["ts"]
    reply1 = await client.chat_postMessage(channel=channel, text="What's up?", thread_ts=ts)
    reply2 = await client.chat_postMessage(channel=channel, text="What's up??", thread_ts=float(ts))
    reply3 = await client.chat_postMessage(channel=channel, text="What's up???", thread_ts=ts)

import asyncio
asyncio.run(main())

As you mentioned, a message with a float ts value for thread_ts is always posted in a channel (not in the thread). This is because the server-side returns a successful result and successfully posts a message in the channel. This means the thread_ts is just ignored because of its data type.

can you shed some light on how you'd like to approach this issue? When a thread_ts is a float, should the SDK return an error, try to cast it as a string, or something else?

As far as I know, this SDK always handles ts values as string. The situation described in this issue arises only when developers change the data type to float regardless of their intention.

So, although it may be more developer-friendly if this SDK gives warnings or raise errors when trying to send ts values as float, I'm still hesitating to add such an extra logic to this SDK at this point. If it's an error, the server-side should tell the error to API callers.

That being said, I do understand this may be a pitfall for developers. So, if other maintainers think we should do something at least for common chat.* API methods, I'm happy to merge the changes.

[iyakushev]

Hi, @seratch. Thank you for you reply!

a message with a float ts value for thread_ts is always posted in a channel (not in the thread)

I find this to be false sometimes. If you try to send a message with a float thread_ts a couple times, it won't send it as a simple message either. I have experienced such behavior a couple days ago when this issue occurred, however I can't confirm it 100% atm. I'll try to test it later today.

As for the errors, I believe it would be logical to check it on the server side and get an error response. However, this might be worthless if the error occurs only in ~5-10% of requests and a simple warning/error from the SDK might be more suitable. But again, the issue is probably uncommon. I've stumbled upon it when I had to check the timestamp of the message against the database and accidently convert it into float. Maybe instead it might be better to simply clarify types in the documentation?

[seratch]

Thanks for your prompt reply!

Maybe instead it might be better to simply clarify types in the documentation?

This sounds great to me 👍

[iyakushev]

@seratch I'm glad to settle on this solution 👍
As for the posting in the channel itself: I did not manage to reproduce it, however I've certainly encountered it before.

Here's a snippet:

....

response = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="Will you thread for me, please?")
response['ts']  # '1602251441.001700'

# all of them respond with Ok
response = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="I won't thread!", thread_ts=1602251441.001700)
response = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="I won't thread!", thread_ts=1602251441.001700)

response = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="Ok, maybe I am...", thread_ts="1602251441.001700")
response = web_client.chat_postMessage(channel=SLACK_CHANNEL, text="I won't thread!", thread_ts=1602251441.001700)

A thread is correctly created.

But if we were to look in the channel, the incorrect thread_ts messages are nowhere to be seen.

This looks odd to me, because of the undetermined behaviour. Yesterday I've managed to reproduce it accidentally:

Could this be considered a bug on the server-side?

[seratch]

I’m not sure we call it a bug but I also encountered the same weird situation.

Probably, after restarting your Slack app (or refreshing the page if you use in a browser), you will see the message posted with float ts in the channel.

[iyakushev]

@seratch Indeed. I've restarted the app and it showed me what a nasty spammer I am 🙃.