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Fomalhaut Weisszwerg
Fomalhaut Weisszwerg

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How to post bulleted lists using Slack Webhook URL.

#python #slack #webhook #api

TL;DR

The "Rich text block" is your friend.

import os from slack_sdk import WebhookClient if __name__ == "__main__": api_client = WebhookClient(url=os.environ["SLACK_WEBHOOK_URL"]) unordered_list_elements: list[dict] = [] for fragment in ["foo", "bar", "baz"]: unordered_list_elements.append( { "type": "rich_text_section", "elements": [{"type": "text", "text": fragment}], } ) api_client.send( blocks=[ { "type": "rich_text", "elements": [ { "type": "rich_text_list", "style": "bullet", "indent": 0, "elements": unordered_list_elements, } ], } ] )
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The official Markdown example does not work

The official document provides a Markdown example:

{ "blocks": [ { "type": "section", "text": { "type": "mrkdwn", "text": "• Detective Chimp\n• Bouncing Boy\n• Aqualad" } } ] }
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But the example does not work properly.

There seems to be a bug in Markdown processing. So you need to use the other way to post a bulleted list via Webhook URL.

"Rich text block"

Rich text block is one of workarounds to the bug.

The basic format of the block is:

[ { "type": "rich_text", "elements": [ { "type": "rich_text_list", "style": "bullet", "elements": [rich_text_sections], } ], } ]
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Note that the type of outermost block must always be set to "rich_text". And a block of bulleted list need to be declared as the inner block.

Finally, define elements of the bulleted list as a list of rich_text_section. The format of rich_text_section is following:

{ "type": "rich_text_section", "elements": [ { "type": "text", "text": value_of_elements } ] }
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If you want to mention someone, set value of "type" "user" instead of "text" such like:

{ "type": "rich_text_section", "elements": [ { "type": "user", "user_id": target_user_id, } ], }
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Similarly, for email address, set "type" "link" like following:

{ "type": "rich_text_section", "elements": [ { "type": "link", "url": f"mailto:{mail_address}", "text": mail_address, } ], }
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Now it is able to post to your Slack workspace using slack_sdk.WebhookClient.send method!

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