andrew at morphoss
Mar 25, 2012, 3:39 PM
Post #2 of 2
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Re: Retrieving recurring appointment instances through CalDAV library
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On Fri, 2012-03-23 at 10:42 +0000, Ben Dalby wrote:
> Hello there,
>
> I have a calendar with a recurring appointment, which is sometimes
> cancelled, and I want to be able to retrieve appointment instances
> through a CalDAV library.
>
> Let's say the appointment is every week day, but in a certain week,
> Thursday's instance is cancelled. So we have
> MON
> TUE
> WED
> FRI
>
> I'm trying to use the IP*Works .NET library to query DAViCal for just
> such a calendar, but my problem is that although DAViCal sends back
> the EXDATE parameter for the cancelled Thursday, it does not return
> RDATE, EXRULE or RECURRENCE-ID.
>
> Example data returned from DAViCal:
> BEGIN:VEVENT
> UID:ff47aab4-9178-46e9-bcf5-253d10e61687
> DTSTART;TZID="GMT Standard Time":20120126T120000 DTEND;TZID="GMT Standard Time":20120126T123000 TRANSP:OPAQUE
> X-OUTLOOK-BUSY-STATUS:2
> LAST-MODIFIED:20120321T142655Z
> DTSTAMP:20120321T142655Z
> CREATED:20120125T140343Z
> SUMMARY:Test Recurring Event
> CLASS:PUBLIC
> RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FR
> LOCATION:Test One Recurring One
> SEQUENCE:2
> DESCRIPTION:Test One Recurring One Description
> EXDATE;TZID="GMT Standard Time":20120202T120000
> END:VEVENT
>
> So at the moment it looks like I'd have to manually implement the
> RRULE property to work out the instance dates myself, using EXDATE as
> a filter on that list.
>
> So my questions are:
> 1. Would it be possible/feasible to change DAViCal so that it sends
> more information back, particularly RDATE?
> 2. Has anyone used a CalDAV API library in any langugage that can
> handle this scenario?
>
> I should say that I've already tried DDay.iCal, and it doesn't handled
> EXDATE correctly. It must be possible, because the eM Client windows
> app shows the right instances quite happily.
Hi Ben,
You can make a REPORT request for a period of time and receive the
events with the RRULE/EXDATE/RDATE expanded server-side. Not sure if
that's helpful to you.
You claim that "although DAViCal sends back the EXDATE parameter for the
cancelled Thursday, it does not return RDATE, EXRULE or RECURRENCE-ID"
but normally DAViCal sends back exactly what data it has been given.
Note that "EXRULE" is not supported by DAViCal in the server-side
expansion of repeat rules - this is deprecated by RFC5545 and very
little (if any) software supports it.
RECURRENCE-ID only applies to instances which have been overridden, so
most events don't contain a RECURRENCE-ID at all, especially if the
override is simply a cancellation as that is handled by adding a date
into the EXDATE property - as in the example you sent.
I suspect that the "expand" property of the calendar-query report,
defined in section 7.8 of RFC4791 is what you are after, though that
will return you all instances of all events in a range, rather than the
single event. But maybe that's also what you're after... :-)
Cheers,
Andrew.
--
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andrew (AT) morphoss (DOT) com +64(272)DEBIAN
I just asked myself... what would John DeLorean do?
-- Raoul Duke
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