How to detect the user on google calendar events push notification callback?

Question

I am trying to sync a booking system with google calendar and google resource as two-way synchronization.

To do that, I creates webhook channels on specific google resource calendars to be aware of creating events (i.e. booking a resource room), updating, and deleting. It works fine — whenever a user creates an event out backend got notified by the google push notification and I can fetch the respective meeting room in our system as well for booking.

But the problem is, I cannot distinguish which user was that! According to the google push notification information I couldn't find any thing about the user information on the callback data. Is there any solution?

Data of header in callback notification:

Host: f73b-98-14-18-68.eu.ngrok.io
User-Agent: APIs-Google; (+https://developers.google.com/webmasters/APIs-Google.html)
Content-Length: 0
Accept: */*
Accept-Encoding: gzip, deflate, br
X-Forwarded-For: 74.125.210.217
X-Forwarded-Proto: https
X-Goog-Channel-Expiration: Thu, 02 Mar 2023 06:34:05 GMT
X-Goog-Channel-Id: 12345678904
X-Goog-Message-Number: 6863357
X-Goog-Resource-Id: szg7mO63iJ_3oMLRGXyv7868CQQ
X-Goog-Resource-State: exists
X-Goog-Resource-Uri: https://www.googleapis.com/calendar/v3/calendars/c_1887qe9rpoms8hdanb029mmhoiira%40resource.calendar.google.com/events?alt=json

---

Google calendar events watch API
Receiving notification

Answer 1

The push notifications are meant to just be a low-throughput way to check for changes to the Calendar, so it only contains the ID of the channel and the calendar ID. Currently there's no way to get specific event info in the push notification.

Your options are to combine the notifications with other APIs. For example:

• Use incremental sync. This uses sync tokens to retrieve only the changed events from the last sync, so you can sync whenever you get a notification. The event object has a creator field so you can know who created it.
• Probably more accurate, you can check the Reports API activities.list with applicationName = calendar to check who made changes to the Calendar and to which events. You can trigger a search after you get a notification and filter results to get all changes from the time after you got the notification. The downside is that there may be some delay for the logs to be generated.

The bottom line is that the push notifications by themselves cannot tell you who made the change, since their job is just to notify you that something changed, but you have a few ways to get the info afterwards.