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When editing recurring events in Calendar, if the event time is changed, should the recur break events that have been edited previously be removed or maintained?

Ezil Kannan
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1 Answers1

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I'm assuming that you are talking about changing the event time for "all" instances.

The iCalendar specification does not mandate anything with regards to such a scenario. A common practice though is to have the client split the recurring event into 2: * the existing recurring event is bounded by adding an UNTIL date in the RRULE. The UNTIL value corresponds to the last instance before the change of time. All instances that had been edited in that time period are preserved. * a new event (with a new UID etc...) gets created, with a DTSTART corresponding to the new time. Edited instances (exceptions) for that time period are removed.

Both events are linked together via a cross referencing RELATED-TO property.

Arnaud Quillaud
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  • Isn't splitting the event into two done only when the event is edited with "this and future/all following" events. What I am referring to is, Supposedly one or two occurrences of a recurring event is edited to different time by "ONLY THIS" option and then if the parent event's start and end time is edited with "ALL EVENTS", should the already edited occurrences be deleted or maintained? Also if the events are to be maintained, the "RECURRENCEID" of these edited occurrences should be appropriately changed right? – Ezil Kannan Oct 13 '17 at 06:58
  • Yes, this corresponds to this and future, which is the only model that really makes sense if you consider that the past is, well, immutable. If you have no other choice but to modify the existing event, and if you want to preserve the exceptions, yes you should modify the RECURRENCE-ID as well. – Arnaud Quillaud Oct 13 '17 at 07:27
  • Whether or not to preserve all exception is a rather difficult question: f you really want to be accurate you would have to consider, for each instance, what caused the exception to be created in the first place. If it is an attendee related change (e.g. attendee has declined a particular instance), then you can remove that exception since the attendee may now be able to join at the new time. Same goes with location if it is a conference room (it may no longer be available at this time). If it is a description change on the other hand, you may want to preserve it. – Arnaud Quillaud Oct 13 '17 at 07:30
  • In my case, it is a time change i.e., say, for a repeat event at 9-10 am everyday, on one specific occurrence the time is changed to 7-8 am. Now the parent event is edited with the time 5-6 am for all events. So, I presume, in this case, it is a better idea to preserve the edited occurrence (7-8am) – Ezil Kannan Oct 13 '17 at 07:51