#PowerPlatformTip 102 – ‘Event Coordination’

💡 Challenge

Organizing event attendees in Power Automate can feel like herding cats. The usual methods often mean everyone gets an alert every time there’s a change, and to make matters worse, everyone can see who else is coming—talk about a lack of privacy!

✅ Solution

Use the Microsoft Graph API with the Update Event call to silently add attendees and hide the guest list by setting the hideAttendees parameter to true.

🔧 How It’s Done

Here’s how to do it:

1. Kick things off with an HTTP request to snag the details on the current event, including who’s already RSVP’d.
   🔸 Use Graph API’s GET /events/{event-id} endpoint.
   🔸 Capture the attendees array from the JSON response.
2. Whip up an array for your new guest, filling in the blanks with their info and email.
   🔸 Construct a new attendee object with emailAddress and type.
   🔸 Ensure you include name and address fields.
3. Bring the new and old attendees together with the magic of the union expression.
   🔸 Merge arrays without duplicates.
   🔸 Use the union(existingAttendees, newAttendees) function.
4. Send that updated list of party-goers back to the event with another HTTP zinger.
   🔸 Use PATCH /events/{event-id} with the updated attendees array.
   🔸 Set "hideAttendees": true in the request body.
5. OR: Take a shortcut and grab the whole setup from my GitHub.
   🔸 See the full JSON flow at https://github.com/MarceLehmann/CodeSnippets/blob/main/EventCoordination.json

🎉 Result

And just like that, you’re adding or tweaking your attendee list on the DL—keeping notification spam to a minimum. Plus, with the attendee list set to private, your event has its own VIP secrecy cloak.

🌟 Key Advantages

🔸 Privacy Enhanced: A cloak of invisibility for your guest list, so attendees can’t peek at others.
🔸 Notification Control: No more alert floods—silent updates only.
🔸 Flexibility: Easily invite one guest or a crowd without extra configuration.

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🎥 Video Tutorial

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🛠️ FAQ

1. How do I authenticate the Graph API request?
Register an Azure AD app, grant it the Calendars.ReadWrite permission, then use Power Automate’s HTTP with Azure AD connector to obtain a token and call the Graph API.

2. What does hideAttendees = true do?
It hides the full guest list so attendees only see their own RSVP and cannot view other participants.

3. Can I remove attendees silently as well?
Yes. Retrieve the current attendees array, filter out the attendee you want to remove, then PATCH the event with the updated array and hideAttendees set to true.

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