So just for additional context:
This meme was brought to you by the following API response scheme:
{ "time": "2007-12-24 18:12", "servertimezone": "Europe/Vienna", "timezoneoffset": -8 }when it could have just been
{ "date": "2007-12-24T18:21:00-07:00" }Anything an API returns should just look like
1720533944.963659.There’s no reason to store dates as anything other than UTC. User-side, sure, timezones are useful. Server doesn’t have to know.
This is absolutely fundamentally wrong. What you’ve described is what Nodatime calls an
Instant, and it’s a very important data class, but there are valid reasons to use other classes.A
LocalDateTimecares about the date and time locally. An event scheduled for 8am every Monday might use this. It would update accordingly if you move locations to a new locale.A
ZonedDateTimecan almost be directly translated into anInstant, except that one time zone might change. If you go into or out of daylight saving time, or your region decides to change its time offset. Oslo time is still Oslo time. You use this if your event occurs at a specific time in a specific location.An
OffsetDateTimeis like aZonedDateTime, but instead of being tied to a specific time zone (e.g. “Oslo time”) it’s tied to a specific UTC offset (e.g. UTC+1).You don’t have to use Nodatime, but you should at least think deeply about what your time objects actually represent and what is the best way to represent them.
See the creator of Nodatime’s presentation about thinking deeply about time for more.
When the API returns UTC, but the system insists on giving you local time… but there’s an extension method that accepts DateTimeOffset?
It should be implemented in people’s brains.
How this goes, usually, is:
Them:…before 6PM.
Me: 6PM… Ours? The server’s? The user’s?
Them: GMT, of course.
Me: So that’s 7PM London right now, and changes to 6PM in November?
Them: What no are you stupid. Always 6PM GMT.
Me:* jumps off a cliff*
Reminds me of a LARP I was on one time. A group of people I was doing stuff with ended up always meeting at 10 because we redefined “10” to mean “whenever we all meet”.
Them: GMT, of course.
Me: So that’s 7PM London right now, and changes to 6PM in November?
Them: What no are you stupid. Always 6PM GMT.
Me:* jumps off a cliff*
Sorry, but are you under the impression that GMT means London time, or that it observes British Summer Time?
Don’t get it. Is this implying GMT has daylight savings?
GMT doesn’t have daylight savings, but most people won’t be as precise in language. Here in Germany, we might also tell people “GMT+2”, even though it changes to GMT+1 in winter. Like, I don’t even know what the correct shorthand would be for our timezone…
