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EWSoftware / PDI

A Personal Data Interchange (PDI) library that implements the vCard (RFC 2426), vCalendar, and iCalendar (RFC 2445) specifications including recurrence pattern generation
Microsoft Public License
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NextInstance skips dates #5

Closed aliciagontarek closed 7 years ago

aliciagontarek commented 7 years ago

If a start date is on the 29th and the NextInstance falls in Feb (based on frequency), that month will be skipped if not a Leap Year. For example, start date is 5/29/17, frequency is 9 months, the next instance displayed is 11/29/18. It also does this if the start date is 2/29 and frequency is yearly, it will only return the leap years. I was able to work around this by setting a ByMonthDay -1 for that scenario, but monthly frequency is more difficult.

EWSoftware commented 7 years ago

This is by design per the specification. If BYxxx rule parts are found that exceed the available scope (in this case Feb 29th in a non-leap year), the instances are ignored. To handle this, you can use the BYSETPOS rule to get the last occurrence that falls on either the 28th or 29th. For example:

FREQ=MONTHLY;INTERVAL=9;BYMONTHDAY=28,29;BYSETPOS=-1

Here, BYMONTHDAY=28,29 computes the 28th and 29th at the given monthly interval and BYSETPOS=-1 limits it to the last in the set. For February of non-leap years, that will be the 28th and for all other months, it will be the 29th.

aliciagontarek commented 7 years ago

Cool. I’ll give that a shot. Thanks!

Alicia Gontarek Senior Developer

From: Eric Woodruff [mailto:notifications@github.com] Sent: Tuesday, May 02, 2017 3:49 PM To: EWSoftware/PDI PDI@noreply.github.com Cc: Alicia Gontarek agontarek@membersolutions.com; Author author@noreply.github.com Subject: Re: [EWSoftware/PDI] NextInstance skips dates (#5)

This is by design per the specification. If BYxxx rule parts are found that exceed the available scope (in this case Feb 29th in a non-leap year), the instances are ignored. To handle this, you can use the BYSETPOS rule to get the last occurrence that falls on either the 28th or 29th. For example:

FREQ=MONTHLY;INTERVAL=9;BYMONTHDAY=28,29;BYSETPOS=-1

Here, BYMONTHDAY=28,29 computes the 28th and 29th at the given monthly interval and BYSETPOS=-1 limits it to the last in the set. For February of non-leap years, that will be the 28th and for all other months, it will be the 29th.

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