Print iCal format for recurring events

Question

I read this answer here which explains how to output an ical file of scheduled items:

How can I use PHP to dynamically publish an ical file to be read by Google Calendar?

My question is what is the ical format for recurring events? Let's say i want to schedule a team meeting every monday at 10 am. What is the ical format for a repeating schedule? Or do i need to print X number of events into the future?

score 3 · Accepted Answer · edited Oct 07 '21 at 05:59

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the ical format is defined by the RFC5545: https://www.rfc-editor.org/rfc/rfc5545

in your case you will need to define only one event and make use of the FREQ property (FREQ=WEEKLY) and COUNT property (COUNT=X)

RRULE:FREQ=WEEKLY;BYDAY=MO;COUNT=X

see https://www.rfc-editor.org/rfc/rfc5545#section-3.3.10 for more details.

edited Oct 07 '21 at 05:59

Community

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answered Oct 23 '12 at 04:31

Auberon Vacher

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Google Calendar was written before RFC 5545 was standardized, so was written to RFC 2445. http://code.google.com/p/google-rfc-2445/ – Mike Samuel Oct 23 '12 at 19:18
I no longer work on that project, so I can't say for sure, but it was at one time. – Mike Samuel Oct 29 '12 at 14:55

score 3 · Answer 2 · answered Oct 23 '12 at 19:21

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Let's say I want to schedule a team meeting every monday at 10 am. What is the ical format for a repeating schedule?

 DTSTART:20121022T100000
 RRULE:FREQ=WEEKLY;BYDAY=MO

specifies a start date of 10am on a Monday, and the RRULE part specifies that it recurs weekly.

You need to put this inside a VEVENT as specified in RFC 2445.

Since no timezone is specified, Google will assume the primary timezone for the calendar to which you are uploading this event.

You do not need to specify a count or a termination date. Google calendar has some internal limit on the number of instances of a recurring event that you can specialize, but unless your team meets regularly for centuries you shouldn't ever run into it.

answered Oct 23 '12 at 19:21

Mike Samuel

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How would one set until for only the time component. For instance, Let's say the scheduled team meeting happens every monday at 10 am - 5pm. What is the ical format for this? – kabangi julius Jul 11 '16 at 09:47
@kabangijulius, The DTSTART specifies when the first instance starts, and a `DTEND:20121022T170000` specifies an end time for the first instance of 5pm on the same day. Subsequent instances differ from the first only in the day but not the hour because FREQ=WEEKLY, not HOURLY. – Mike Samuel Jul 11 '16 at 23:24

score 2 · Answer 3 · edited Oct 07 '21 at 06:06

You can use the RRULE and FREQ properties to accomplish this as described in RFC5545. In your case it would look something like this:

DTSTART:20121029T100000Z
RRULE:FREQ=WEEKLY;BYDAY=MO;UNTIL=20131028T110000Z

You can also set other ways to limit the number of occurances (like number of recurring events) or just have it repeat forever. However, putting a reasonable limit instead of infinite repetitions is more polite to your users if you ask me.

Print iCal format for recurring events

3 Answers3