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icalendarmicrosoft-graph-apioutlook-restapi

Identify same/related calendar event from different calendars

I need to retrieve the attendee list from an organizer's calendar. To do this, I need to identify with certainty the same event in the another user's calendar.

Exchange is linking the related events, but that property might not be exposed over Microsoft Graph API and the Event id does not match.

So far I could identify that iCalUId does match. Of course, start and end dates should match also. The subject will most likely not match because rooms often transform this property.

  1. Can anyone confirm, that iCalUId is always the same for related events in different calendars?

  2. Can I filter Microsoft Graph events by iCalUId property (or directly access it using this key)?

Update:

I have found this article, which theoretically confirms my first question. I would appreciate if somebody could confirm this based on practical experience.

Solution

  • The iCalUId property is static, even across external recipients. This iCalUId property reflects the UID property defined in the iCalendar specification (RFC 5545 § 3.8.4.7) as a "persistent, globally unique identifier for the calendar component".

    As for pulling it from Microsoft Graph, you can use the $filter query parameter of the events collection to fetch a given iCalUId:

    /v1.0/me/events?$filter=iCalUId eq '{UID}'

    You can try this in Graph Explorer using this sample.