Python datetime utcnow vs Luxon Datetime.fromMillis?-CodePudding

I'm trying to wrap my head in understanding the implication of using .utcnow vs .now on Python's datetime.

Here's the reason of my confusion: I live in France. Right now, we have a 1 hour on the UTC timezone (CET timezone in winter (now) / CEST ( 2) timezone in summer).

If I take the following value :

dt = datetime.datetime.utcnow()
dt.strftime('%c') # Thu Dec  9 16:17:38 2021
int(dt.timestamp()) # 1639063064

This is correct as it is, in France right now, 17h17. So, from my understanding, that timestamp, 1639063064 is the UTC representation of the time since EPOCH.

But if I test this value in the website Epoch Converter, I get

GMT: Thursday 9 December 2021 15:17:44
Your time zone: jeudi 9 décembre 2021 16:17:44 GMT 01:00

It seems that the website ALSO substract my timezone to an already "substracted" value, ending in removing twice the timezone and causing an invalid value.

The real confusion is when I tried to import that UTC timestamp to Luxon on my front app, doing the following doesn't work :

DateTime.fromMillis(parseInt(ts), { zone: 'utc' }).toLocal().setLocale('en')

I'm one hour behind.

How can I "tell" Luxon that the current TS is in the UTC timezone, and calling toLocal will apply the proper user's timezone ?

CodePudding user response：

It seems that the website ALSO substract my timezone t

No, epochconverter.com isn't doing anything. The value 1639063064 really does represent 2021-12-09T15:17:44Z. That's not the value you want.

I'm no Python expert, but I believe the problem is the combination of this utcnow() behavior (emphasis mine):

Return the current UTC date and time, with tzinfo None.

This is like now(), but returns the current UTC date and time, as a naive datetime object.

And this timestamp() behavior:

Naive datetime instances are assumed to represent local time and this method relies on the platform C mktime() function to perform the conversion.

It sounds like you want to follow this advice:

An aware current UTC datetime can be obtained by calling datetime.now(timezone.utc).

So just change your first line to:

dt = datetime.now(timezone.utc)

... and it should be okay.