I am trying to compare the current date and time with dates and times specified in models using comparison operators:
if challenge.datetime_start <= datetime.now() <= challenge.datetime_end:
The script errors out with:
TypeError: can't compare offset-naive and offset-aware datetimes
The models look like this:
class Fundraising_Challenge(models.Model):
name = models.CharField(max_length=100)
datetime_start = models.DateTimeField()
datetime_end = models.DateTimeField()
I also have django using locale date and times.
What I haven't been able to find is the format django uses for DateTimeField(). Is it naive or aware? And how do I get datetime.now() to recognize locale datetime?
By default, the datetime
object is naive
in Python, so you need to make both of them either naive or aware datetime
objects. This can be done using:
import datetime
import pytz
utc=pytz.UTC
challenge.datetime_start = utc.localize(challenge.datetime_start)
challenge.datetime_end = utc.localize(challenge.datetime_end)
# now both the datetime objects are aware, and you can compare them
Note: This would raise a ValueError
if tzinfo
is already set. If you are not sure about that, just use
start_time = challenge.datetime_start.replace(tzinfo=utc)
end_time = challenge.datetime_end.replace(tzinfo=utc)
BTW, you could format a UNIX timestamp in datetime.datetime object with timezone info as following
d = datetime.datetime.utcfromtimestamp(int(unix_timestamp))
d_with_tz = datetime.datetime(
year=d.year,
month=d.month,
day=d.day,
hour=d.hour,
minute=d.minute,
second=d.second,
tzinfo=pytz.UTC)
datetime.datetime.now
is not timezone aware.
Django comes with a helper for this, which requires pytz
from django.utils import timezone
now = timezone.now()
You should be able to compare now
to challenge.datetime_start
USE_TZ=True
then timezone.now()
returns a timezone-aware datetime object even if pytz
is not installed (though it might be recommended to install for other reasons).
One line of code solution
if timezone_aware_var <= datetime.datetime.now(timezone_aware_var.tzinfo):
pass #some code
Explained version
# Timezone info of your timezone aware variable
timezone = your_timezone_aware_variable.tzinfo
# Current datetime for the timezone of your variable
now_in_timezone = datetime.datetime.now(timezone)
# Now you can do a fair comparison, both datetime variables have the same time zone
if your_timezone_aware_variable <= now_in_timezone:
pass #some code
Summary
You must add the timezone info to your now()
datetime.
However, you must add the same timezone of the reference variable; that is why I first read the tzinfo
attribute.
Disable time zone. Use challenge.datetime_start.replace(tzinfo=None);
You can also use replace(tzinfo=None)
for other datetime.
if challenge.datetime_start.replace(tzinfo=None) <= datetime.now().replace(tzinfo=None) <= challenge.datetime_end.replace(tzinfo=None):
no third-party, only the native datetime module.
from datetime import datetime, timedelta, timezone
time1 = datetime.strptime('2021-07-15T00:22:02+0000', '%Y-%m-%dT%H:%M:%S%z')
time2 = datetime(2021, 7, 15, tzinfo=timezone(offset=timedelta()))
if time1 < time2:
print(True)
datetime.now().replace(tzinfo=timezone(offset=timedelta()))
It is working form me. Here I am geeting the table created datetime and adding 10 minutes on the datetime. later depending on the current time, Expiry Operations are done.
from datetime import datetime, time, timedelta
import pytz
Added 10 minutes on database datetime
table_datetime = '2019-06-13 07:49:02.832969' (example)
# Added 10 minutes on database datetime
# table_datetime = '2019-06-13 07:49:02.832969' (example)
table_expire_datetime = table_datetime + timedelta(minutes=10 )
# Current datetime
current_datetime = datetime.now()
# replace the timezone in both time
expired_on = table_expire_datetime.replace(tzinfo=utc)
checked_on = current_datetime.replace(tzinfo=utc)
if expired_on < checked_on:
print("Time Crossed)
else:
print("Time not crossed ")
It worked for me.
So the way I would solve this problem is to make sure the two datetimes are in the right timezone.
I can see that you are using datetime.now()
which will return the systems current time, with no tzinfo set.
tzinfo is the information attached to a datetime to let it know what timezone it is in. If you are using naive datetime you need to be consistent through out your system. I would highly recommend only using datetime.utcnow()
seeing as somewhere your are creating datetime that have tzinfo associated with them, what you need to do is make sure those are localized (has tzinfo associated) to the correct timezone.
Take a look at Delorean, it makes dealing with this sort of thing much easier.
utcnow
won't add timezone info
You are trying to set the timezone for date_time which already has a timezone. Use replace
and astimezone
functions.
local_tz = pytz.timezone('Asia/Kolkata')
current_time = datetime.now().replace(tzinfo=pytz.utc).astimezone(local_tz)
Just:
dt = datetimeObject.strftime(format) # format = your datetime format ex) '%Y %d %m'
dt = datetime.datetime.strptime(dt,format)
So do this:
start_time = challenge.datetime_start.strftime('%Y %d %m %H %M %S')
start_time = datetime.datetime.strptime(start_time,'%Y %d %m %H %M %S')
end_time = challenge.datetime_end.strftime('%Y %d %m %H %M %S')
end_time = datetime.datetime.strptime(end_time,'%Y %d %m %H %M %S')
and then use start_time
and end_time
Success story sharing
tzinfo
doesn't do any conversion, making the comparison incorrect.utc = pytz.utc
to prevent the pylint errorNo value for argument 'dt' in unbound method call (no-value-for-parameter)
. pytz linkutc
timezone fromdatetime
'stimezone
module.timezone.utc
.