Slack invite integration for Google Forms

how-to.md

1. Create a Google Form with a field to collect email addresses. Pro-tip: use Data Validation to validate string is valid email.
2. Click View Responses to view form responses in Google Spreadsheets.
3. Open menu Tools > Script editor...
4. Paste in Google App Script below and make the following changes:
   • Create a Slack API token and replace the value of SLACK_API_TOKEN.
   • Replace "YOUR_TEAM_NAME" with your team's name in the value for SLACK_API_INVITE_URL.
   • Make sure EMAIL_FIELD_NAME corresponds to the header text of your Google Spreadsheet's email column.
5. Open menu Resources > Current project's triggers and add a new trigger: onFormSubmit, From spreadsheet, On form submit. Click Save and accept the authorization request to use the script.
6. You can optionally configure notifications to receive error messages by email.

invite-user.js

var SLACK_API_TOKEN = 'xxxx-xxxxxxxxxx-xxxxxxxxxx-xxxxxxxxxxx-xxxxxxxxxx';
var SLACK_API_INVITE_URL = 'https://YOUR_TEAM_NAME.slack.com/api/users.admin.invite';
var EMAIL_FIELD_NAME = 'E-mail Address';

function inviteUser(email) {

  var data = {
    email: email,
    token: SLACK_API_TOKEN,
    set_active: 'true'
  };
  
  var options = {
    method: 'POST',
    payload: data
  };

  UrlFetchApp.fetch(SLACK_API_INVITE_URL, options);
}

function onFormSubmit(e) {
  var email = e.namedValues[EMAIL_FIELD_NAME][0];
  inviteUser(email);
}

Relevant links:
https://api.slack.com/authentication/token-types
https://api.slack.com/docs/rate-limits
https://api.slack.com/methods/admin.users.invite
The last one says it's only available for "Enterprise Grid".

The schema has changed a bit so it's definitely not plug-and-play anymore.