Slack has a convenient API “Outgoing Webhook” that you can use when you want to write messages posted on Slack’s channel to Google Spreadsheet.
What are Outgoing Webhooks?
An API/service for sending Slack messages to external services in the Slack App directory.
Outgoing WebhooksOutgoing webhooks was a quirky way to send your own server a webhook when messages met a narrow set of criteria. We recommend building Slack apps instead!
Use outgoing webhooks
First, go to the Slack App directory screen from “Settings and administration > Manage apps” in the Slack app.
If you search for Outgoing Webhook in the Slack App directory, you should see results.
Press “Add to Slack” to add the application.
Add Outgoing Webhook Integration
Select Add Outgoing Webhook Integration.
After adding the integration, you select the channels you want to get messages from.
Set the deployed URL on the GAS side that will be the Webhook in this URL part.
Press “Save settings” to complete the settings.
Now you can write data from Slack to Google Sheets.
Next time, I would like to use this integration to set data in Google Spreadsheet on the GAS side.
Slack has a convenient mechanism called “Outgoing Webhook”, so please refer to it.