[Bug]: Event update email unclear with recurrence exceptions

[ChristophWurst]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• Nextcloud Server is running on 64bit capable CPU, PHP and OS.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

Deleting an instance of a recurring event sends out an event update/invite without any useful information about what really changed.

The email says "Time: "

Steps to reproduce

1. Create an event with one attendee that recurs weekly for three times
2. Accept the invitation as the other user
3. Delete the second occurrence as the organizer

BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
BEGIN:VEVENT
CREATED:20230607T094533Z
DTSTAMP:20230607T094848Z
LAST-MODIFIED:20230607T094848Z
SEQUENCE:4
UID:5e8a4ae6-39d7-4cb1-91e0-f04036be45d9
DTSTART;TZID=Europe/Vienna:20230607T133000
DTEND;TZID=Europe/Vienna:20230607T153000
STATUS:CONFIRMED
SUMMARY:Zoo party
ATTENDEE;[email protected];CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED;ROL
 E=REQ-PARTICIPANT;SCHEDULE-STATUS=1.1:mailto:[email protected]
ORGANIZER;CN=Christoph Wurst:mailto:[email protected]
RRULE:FREQ=WEEKLY;COUNT=3;BYDAY=WE
LOCATION:At the zoo
DESCRIPTION:Bring your own food
EXDATE;TZID=Europe/Vienna:20230614T133000
BEGIN:VALARM
ACTION:DISPLAY
TRIGGER;RELATED=START:-PT1H
END:VALARM
END:VEVENT
END:VCALENDAR

Expected behavior

The attendee receives an email that says something like "Time: , recurring weekly except ".

Installation method

None

Nextcloud Server version

master

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

n/a

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

nextcloud/calendar#3919

[ChristophWurst]

The issue is broad. Some scenarios I've experienced in the past

1. Organizer cancels one of the instances of the recurrence
2. Organizer moves one of the occurrences
3. The recurring event changes time/day for all future instances
4. The recurrence ends

[SebastianKrupinski]

Hello all,

After looking in to this... yes the notification emails for recurring events are lacking...

Some possible changes to improve this could be...

Time Section

Currently, the time section of the email only shows the day and time of the first event.

"Wed, Apr 22, 2024 10.00AM - 11.00AM (America/Toronto)".

A possible alternative to this could be to change this line to something more informative for recurring events.

"Weekly on Mo, We, Fr between 10.00AM - 11.00AM (America/Toronto)"

"Weekly on Mo, We, Fr between 10.00AM - 11.00AM (America/Toronto) until Fri, May 10, 2024" (Until would be also calculated for recurrence after count)

"Monthly on the 20th between 10.00AM - 11.00AM (America/Toronto)"

"Monthly on the 1st Friday between 10.00AM - 11.00AM (America/Toronto)"

"Yearly on the 20th of May between 10.00AM - 11.00AM (America/Toronto)"

Next Recurrence Section

Currently the recurring event email notification does not have a section that indicates when the next occurrence is, this is fine if the recurrence does not change, in the case that there is a change made to a recurrence a simple to read section of when the next event occurs would be very help full. Something like...

• Occurring On
  "Mon, Apr 29, 2024 10.00AM - 11.00AM (America/Toronto)"
  "Wed, May 1, 2024 10.00AM - 11.00AM (America/Toronto)"
  "Fri, May 3, 2024 10.00AM - 11.00AM (America/Toronto)"

Changed Recurrence Section

Currently there is no indication of any time changes or deletions made to any occurrences. This could be made more clear with a additional section that list all changes made..

• Occurring Changes
  "Moved: Fri, May 3, 2024 10.00AM - 11.00AM (America/Toronto) to Fri, May 3, 2024 8.00AM - 9.00AM (America/Toronto)"
  "Cancelled: Fri, May 3, 2024 10.00AM - 11.00AM (America/Toronto)"

Thanks
Sebastian

[jancborchardt]

Sounds great to me @SebastianKrupinski, very thorough!

Only one details about the time format, cause it looks a bit like non-standard formatting (let me know if this comes from a library though). Instead of

10.00AM - 11.00AM

It should be:

10:00 am – 11:00 am

• colon : to separate hours and minutes
• en-dash – to separate from/to
• "am" and "pm" lowercase and separated with a space from the time

[SebastianKrupinski]

@jancborchardt Awesome.

The time formatting was just something I typed in as examples. The actual formatting can be what ever we want it to be.

Sebastian

[jancborchardt]

@SebastianKrupinski cool, in that case best get what a localized library spits out, so it's translated and universal. :)

[SebastianKrupinski]

@jancborchardt yes I will make sure its localized