I have a case where I get an CET datetime (via my API) and I want to save it in my django database.
When I do this I always get a runtime warning:
datetime.fromtimestamp(last_content_update)
When I add the replace part I don't get the error but my date is not correct (1h shift):
datetime.fromtimestamp(last_content_update).replace(tzinfo=utc)
Any idea how I can load my datetime timezone aware?
Ok, finally I found out that the fromtimestamp() takes an timezone parameter!
Just do it like this:
datetime.fromtimestamp(last_content_update, tz=pytz.timezone("Europe/Paris"))
Here is a link to the documentation.
You need to do this in two steps:
First, make the datetime timezone-aware - in your case, using the CET (Central European Time) timezone.
Second, convert the datetime to UTC before saving it. This is because Django stores datetimes as UTC:
When support for time zones is enabled, Django stores datetime
information in UTC in the database...
This can be done like this:
import pytz
from django.utils import timezone
# Convert the naive datetime into a CET datetime
local_datetime = timezone.make_aware(naive_datetime, pytz.timezone('CET'))
# Convert the CET datetime to UTC
utc_datetime = local_datetime.astimezone(timezone.utc)
# Now it can be saved in the database on a model field
MyDateModel.objects.create(title='Another date model',
created=utc_datetime)
Related
I have the following timestamp 1550588656 which translates to 2019-02-19 15:04:16+00:00 in UTC time convention.
I want to convert it to my country's time convention (UTC or GMT -3 in this time of the year) so it should translate to 2019-02-19 12:04:16+00:00
I have read on other SO questions that first I have to convert the timestamp to an UTC aware Datetime object and then localize it, I'm doing it like this
# string format time
naive_datetime = datetime.fromtimestamp(timestamp).strftime('%Y-%m-%d %H:%M:%S')
# string parse time
naive_datetime = datetime.strptime(naive_datetime, "%Y-%m-%d %H:%M:%S")
# make naive Datetime object UTC aware
utc_datetime = naive_datetime.replace(tzinfo=pytz.UTC)
So now it's not a naive Datetime object, from here I should be able to localize it to my country's timezone. In Python that is pytz.timezone('America/Santiago')
So it should go something like this
cltime = pytz.timezone('America/Santiago')
local_datetime = utc_datetime.astimezone(cltime)
But I'm getting 2019-02-19 09:04:16-03:00 (UTC or GTM -6 ) as a result and I don't know why.
Can someone explain? My intuition tells me it's probably a simple thing I'm not looking at, but I've spent some minutes in it and I haven't been able to tell yet.
If you look at the documentation for fromtimestamp:
Return the local date and time corresponding to the POSIX timestamp
So the problem is that it is already doing a conversion from UTC to the local time, and you're doing it a second time.
First of all you have epoc time (UTC timestamp). You need to convert it into datetime object (native) which is followed by converting native time to aware time and than finally convert it to your local time.
Convert your timestamp to native datetime object
native_datetime = datetime.fromtimestamp(1550588656)
convert native datetime object to aware time (add timezone info, will add timezone info to native timezone UTC for current)
import pytz
utc_time = native_datetime.replace(tzinfo=pytz.timezone("UTC"))
localising aware datetime to your local datetime
local_time = utc_time.astimezone(pytz.timezone("America/Santiago"))
You can replace "America/Santiago" with your local time zone
I think this would help you to solve your problem. Thanks!
I am trying to parse an RSS feed. Entries in the feed have date elements like:
<dc:date>2016-09-21T16:00:00+02:00</dc:date>
Using feedparser, I try to do:
published_time = datetime.fromtimestamp(mktime(entry.published_parsed))
But the problem is that I seem to be getting the wrong time stored in the database. In this particular case, the datetime is stored as:
2016-09-21 13:00:00
... when I would expect 14:00 - the correct UTC time.
I assume the problem is in our django settings, where we have:
TIME_ZONE = 'Europe/Berlin'
Because when I switch to:
TIME_ZONE = 'UTC'
... the datatime is stored as correct UTC time:
2016-09-21 14:00:00
Is there any way to keep the django settings as they are, but to parse and store this datetime correctly, without the django timezone setting affecting it?
EDIT:
Maybe it's more clear like this...
print entry.published_parsed
published_time = datetime.fromtimestamp(mktime(entry.published_parsed))
print published_time
localized_time = pytz.timezone(settings.TIME_ZONE).localize(published_time, is_dst=None)
print localized_time
time.struct_time(tm_year=2016, tm_mon=9, tm_mday=21, tm_hour=14, tm_min=0, tm_sec=0, tm_wday=2, tm_yday=265, tm_isdst=0)
2016-09-21 15:00:00
2016-09-21 15:00:00+02:00
feedparser's entry.published_parsed is always a utc time tuple whatever the input time string is. To get timezone-aware datetime object:
from datetime import datetime
utc_time = datetime(*entry.published_parsed[:6], tzinfo=utc)
where utc is a tzinfo object such as datetime.timezone.utc, pytz.utc, or just your custom tzinfo (for older python versions).
You shouldn't pass utc time to mktime() that expects a local time. Same error: Have a correct datetime with correct timezone.
Make sure USE_TZ=True so that django uses aware datetime objects everywhere. Given a timezone-aware datetime object, django should save it to db correctly whatever your TIME_ZONE or timezone.get_current_timezone() are.
Have you tried using datetime.utcfromtimestamp() instead of datetime.fromtimestamp()?
As a secondary solution, you can get the unparsed data (I believe it's available as entry.published?) and just use python-dateutil to parse the string, then convert it to pytz.utc timezone like this.
>>> import pytz
>>> from dateutil import parser
>>> dt = parser.parse('2016-09-21T16:00:00+02:00')
>>> dt
datetime.datetime(2016, 9, 21, 16, 0, tzinfo=tzoffset(None, 7200))
>>> dt.astimezone(pytz.utc)
datetime.datetime(2016, 9, 21, 14, 0, tzinfo=<UTC>)
Use
published_time = pytz.utc.localize(datetime.utcfromtimestamp(calendar.timegm(parsed_entry.published_parsed)))
Feedparser can parse a large range of date formats, you can find them here.
As you can see in feedparser/feedparser/datetimes/__init__.py, the built-in function from Feedparser _parse_date does the following:
Parses a variety of date formats into a 9-tuple in GMT
This means that in parsed_entry.published_parsed you have a time.struct_time object in GMT timezone.
When you convert it to a datetime object using
published_time = datetime.fromtimestamp(mktime(parsed_entry.published_parsed))
the problem is that mktime assumes that the passed tuple is in local time, which is not, it's GMT/UTC! Other than that you don't properly localize the datetime object at the end of the conversion.
You need to replace that conversion with the following, remembering that Feedparser returns a GMT struct_time, and localize that with the timezone you like (UTC for the sake of simplicity).
You use calendar.timegm, which gives the number of seconds between epoch and the date passed as a parameter, assuming that the passed object is in UTC/GMT (we know from Feedparser it is)
You use utcfromtimestamp to obtain a naive datetime object (which we know represents a datetime in UTC, but Python does not at this moment)
With pytz.utc.localize you properly localize in UTC the datetime object.
Example:
import calendar
from datetime import datetime
import pytz
localized_dt = pytz.utc.localize(datetime.utcfromtimestamp(calendar.timegm(parsed_entry.published_parsed)))
As long as you are consistent, it doesn't matter if you use fromtimestamp or utcfromtimestamp. If you use fromtimestamp you need to tell Python that the datetime object you created has the local timezone. Supposing you are in Europe/Berlin, this is also fine:
pytz.timezone('Europe/Berlin').localize(datetime.fromtimestamp(calendar.timegm(parsed_entry.published_parsed)))
Were parsed_entry.published_parsed also in local timezone, mktime must be used in place of calendar.timegm.
As an alternative you can parse yourself the data string you get from Feedparser parsed_entry['published']
from dateutil import parser
localized_dt = parser.parse(parsed_entry['published'])
You can check that the following returns True:
parser.parse(parsed_entry['published']) == pytz.utc.localize(datetime.utcfromtimestamp(calendar.timegm(parsed_entry.published_parsed)))
The Django TIME_ZONE setting doesn't actually matter, because it's used only for visualization purposes or to automatically convert naive datetimes.
When USE_TZ is True, this is the default time zone that Django will use to display datetimes in templates and to interpret datetimes entered in forms.
What is important is to always use properly localized datetimes, no matter which time zone is used. As long as they are not in naive format, they will be properly handled by Django.
I'd like to use the timestamp from a database result and convert it to my locale time format. The timestamp itself is saved in UTC format: 2015-03-30 07:19:06.746037+02. After calling print value.strftime(format) with the format %d.%m.%Y %H:%M %z the output will be 30.03.2015 07:19 +0200. This might be the correct way to display timestamps with timezone information but unfortunately users here are not accustomed to that. What I want to achieve is the following for the given timestamp: 30.03.2015 09:19. Right now I'm adding two hours via
is_dst = time.daylight and time.localtime().tm_isdst > 0
utc_offset = - (tine.altzone if is_dst else time.timezone)
value = value + timedelta(seconds=utc_offset)
I was wondering if there is a more intelligent solution to my problem. (timestamp.tzinfo has a offset value, can/should this be used instead? The solution needs to be DST aware too.)
In your question the timestamp is already in desired timezone, so you don't need to do anything.
If you want to convert it to some other timezone you should be able to use;
YourModel.datetime_column.op('AT TIME ZONE')('your timezone name')
or,
func.timezone('your timezone name', YourModel.datetime_column)
in SQLAlchemy level.
On python level, consider using pytz
You don't need to do conversions manually when you use time zone aware database timestamps unless the timezone you want to display is different from the system timezone.
When you read and write datetime objects to the database the timezone info of the datetime object is taken into account, this means what you get back is the time in the local time zone, in your case +0200.
This SO post answers how to get local time from a timezoned timestamp.
Basically, use tzlocal.
import time
from datetime import datetime
import pytz # $ pip install pytz
from tzlocal import get_localzone # $ pip install tzlocal
# get local timezone
local_tz = get_localzone()
# test it
# utc_now, now = datetime.utcnow(), datetime.now()
ts = time.time()
utc_now, now = datetime.utcfromtimestamp(ts), datetime.fromtimestamp(ts)
local_now = utc_now.replace(tzinfo=pytz.utc).astimezone(local_tz) # utc -> local
assert local_now.replace(tzinfo=None) == now
I am am given the following:
The offset of the user's time from GMT in minutes. For example, GMT+10 is
timezone_offset = 600.
I use pytz to get the current time in UTC:
from datetime import datetime
from pytz import timezone
now_utc = datetime.now(timezone('UTC'))
How do I the get the users time?
Thanks
You can add timedelta(hours=10) or timedelta(minutes=600) to the datetime object containing the UTC time.
However, it would be a better idea to store the timezone instead of the offset and then use Python's timezone functions to convert the time.
Please help me to change datetime object (for example: 2011-12-17 11:31:00-05:00) (including timezone) to Unix timestamp (like function time.time() in Python).
Another way is:
import calendar
from datetime import datetime
d = datetime.utcnow()
timestamp=calendar.timegm(d.utctimetuple())
Timestamp is the unix timestamp which shows the same date with datetime object d.
import time
import datetime
dtime = datetime.datetime.now()
ans_time = time.mktime(dtime.timetuple())
Incomplete answer (doesn't deal with timezones), but hopefully useful:
time.mktime(datetime_object.timetuple())
** Edited based on the following comment **
In my program, user enter datetime, select timezone. ... I created a timezone list (use pytz.all_timezones) and allow user to chose one timezone from that list.
Pytz module provides the necessary conversions. E.g. if dt is your datetime object, and user selected 'US/Eastern'
import pytz, calendar
tz = pytz.timezone('US/Eastern')
utc_dt = tz.localize(dt, is_dst=True).astimezone(pytz.utc)
print calendar.timegm(utc_dt.timetuple())
The argument is_dst=True is to resolve ambiguous times during the 1-hour intervals at the end of daylight savings (see here http://pytz.sourceforge.net/#problems-with-localtime).