[Bug]: entered date is shifted back one day in Birthday

[alexanderdd]

Steps to reproduce

1. (not sure if that is relevant) be located in Brazil (with correct timezone setting of computer/browser), NC server is in Germany
2. in settings > personal info, set birthday date to (example) 31.1.1986
3. birthday is displayed as 30.1.1986

Expected behavior

entered date = displayed date

Nextcloud Server version

30

Additional info

this is on c.nc.com - can't check most of the other needed info

maybe related? nextcloud/calendar#6528

same for settings > Availability > Absence #61584

[ChristophWurst]

This sounds similar to #42139.

[SebastianKrupinski]

Tested. Confirmed.

Issue

The issue is the way that javascript new Date() functions

server/apps/dav/src/components/AbsenceForm.vue

Line 84 in c21888e

firstDay: firstDay ? new Date(firstDay) : new Date(),

The date is sent from the backend to the frontend as a string "2024-12-31", without time or timezone. Javascript Date() creates the date in UTC timezone because there is no timezone in the string, then is applies the browsers time zone to the UTC date. This then causes the date to roll back one day, if the browser timezone has a positive offset (grater than UTC).

Example:

2024-12-31 -> in UTC time zone is 2024-12-31 T00:00:00

2024-12-31 -> in America/Toronto time zone is 2024-12-30 T19:00:00

2024-12-31 -> in Australia/Sydney time zone is 2024-12-31 T11:00:00

Solution

• Send apply timezone and full date/time string with time zone from backend
• Send time zone from backend and calculate date with timezone offset