Message Attachments missing when posting message to Slack App Home channel

Question

I've built a Workspace App for Slack, which now comes with a channel (under the Apps header), where a user can send messages to the app itself. This triggers a message.app_home event, that my backend receives. I want to respond to that message, using chat.postMessage, but only the message text appears in the response. None of the attachments I send along appear in the channel. Returning this structure as part of a JSON response to a Slash Command request works correctly.

Here are the attachments structure I sending along:

(
    {
        "title": "Create a space, optionally setting its name and adding other users",
        "text": "`/luffa create [space name] [teammates]`\nExample: `/luffa create Marketing Campaign 2018 @john @kate`",
        "color": SLACK_COLOR,
    },
    {
        "title": "Start a new meeting, optionally strating it in the space matching the provided name",
        "text": "`/luffa start [space name]`\nExample: `/luffa start Marketing Campaign 2018`",
        "color": SLACK_COLOR,
    },
    {
        "title": "Search Luffa",
        "text": "`/luffa search [query]`\nExample: `/luffa search interviews before:Yesterday `",
        "color": SLACK_COLOR,
    },
    {
        "text": "There is more help available in our Help Center: https://help.okluffa.com/",
    },
)

I am using the slackclient Python library to wrap my calls to the Slack API.

There is no error message returned and the structure seems to be correct based on the documentation. Is there something missing there?

score 1 · Answer 1 · answered Jul 17 '18 at 19:48

1

Something small to check - try removing the extra commas on each last value in your attachments structure, as those are causing validation errors when plugged into the Slack message tester here:

answered Jul 17 '18 at 19:48

Adil B

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Thank you for taking the time to answer. However, it turns out the issue was with the Python library I was using to wrap my calls to the API. – JSTL Jul 18 '18 at 14:22
Glad you figured it out! Thanks for posting your answer :) – Adil B Jul 18 '18 at 17:05

score 1 · Accepted Answer · answered Jul 18 '18 at 14:32

The issue turned out that the data structure I was passing to slackclient 1.2.1 was a tuple of objects. The library will only serialize as JSON list or dict objects. (See slackrequest.py, line 94, if isinstance(v, (list, dict)):). Passing a tuple, or any other iterable for that matter, will not be serialized correctly and the Slack API will disregard the attachments. That was not an issue with a JSON response to a request, since Python's JSON serializer converts all iterables to a JSON array.

I solved the issue by passing in a list to the slackclient method.

Message Attachments missing when posting message to Slack App Home channel

2 Answers2