Get recurrence of CalendarEvent in G-Suite Addon

Question

I'm working on a Google Calendar addon that synchronizes event data with an external service. It's easy to get data like title, description, dates etc. of an event and I can even check wether it's a recurring event or not with event.isRecurringEvent().

What I can't seem to find out is how to get the recurrence rule(s) for a specific event. Is this even possible? Neither https://developers.google.com/apps-script/reference/calendar/calendar-event nor https://developers.google.com/apps-script/reference/calendar/calendar-event-series have something like getRecurrenceRule()

Thanks for any help!

Answer 1

If I understand you correctly, you have a CalendarEvent in Google Apps Script and you want to get its recurrence.

Since, as you said, there is not a method like getRecurrenceRule(), you will have to activate the Advanced Calendar Service and call Events: get to get information on the recurrence of the event. If event is your CalendarEvent, you can retrieve the information on the recurrence by doing the following:

eventId = event.getId().split("@")[0];
var eventFromAPI = Calendar.Events.get(calId, eventId);
var recurrence = eventFromAPI["recurrence"];
return recurrence;

Notes:

• I'm using split to remove the characters after @ of the string returned by event.getId(), because it appends @google.com.
• The recurrence is a "list of RRULE, EXRULE, RDATE and EXDATE lines for a recurring event, as specified in RFC5545". Even though this has information of the recurrence of the event, it's not an instance of the Apps Script class RecurrenceRule. As far as I know, there is no way to return that.

Reference:

• Advanced Calendar Service
• Events: get
• Calendar API: Event resource
• RecurrenceRule

I hope this is of any help.