Can't compare naive and aware datetime.now() <= challenge.datetime_end

Question

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?

Answer 1

I used this line when deploying locally:

now = datetime.datetime.today().replace(tzinfo=pytz.UTC)
if item.date_close >= now >= item.date_open:

However, during production, it raised the same error. The possible solution is to check your datatype in postgresql database, change it to timestamptz.

Answer 2

[Option 1] To make both objects datetime aware

Sample code :

from datetime import datetime, timezone
# If `challenge_datetime_end` is already timezone-aware, ensure `now()` is also aware
now_aware = datetime.now(timezone.utc)

# Now you can safely compare `now_aware` with `challenge_datetime_end`
if now_aware < challenge_datetime_end:
   # Your logic here

[Option 2] To make both objects datetime naive

Sample code :

from datetime import datetime, timezone
# Assuming `challenge_datetime_end` is timezone-aware
challenge_datetime_end_naive = challenge_datetime_end.replace(tzinfo=None)
    
# Now you can compare it with the naive `datetime.now()`
if datetime.now() < challenge_datetime_end_naive:
# Your logic here

Answer 3

From time to time this error pops up in my notebooks... I have no clue why.

My datetime objects are usually in arrays. I tried some of the answers above, but the way I found to deal with this problem is

import numpy as np
import matplotlib.dates as mdates

array_with_datetime = np.array( 
                          mdates.num2date( 
                                     mdates.date2num( 
                                                 array_with_datetime)))

not elegant, but it works. If I not use the np.array, it returns a list.

Answer 4

To make your datetime object timezone aware from naive, simply add the function:

datetimeObject.astimezone()

Answer 5

In my case I have controlled the time zone with pytz and I have converted the date to native with timezone from django.utils:

import pytz
from django.utils import timezone

def _my_method(native_date, timezone):
    aware_date = datetime.now(pytz.timezone(timezone))
    return timezone.make_naive(aware_date) >  native_date

Also you can make aware the native date with timezone.make_aware

Answer 6

If you're using Python 3.6 and newer, you can leverage the native datetime capability.

utc_date = datetime.datetime.fromtimestamp(0, datetime.timezone.utc)

Answer 7

If you are using SQLAlchemy and storing the DateTime then you can store it with timezone info. This will allow you to compare that DateTime with timezone-aware DateTimes. Example Column definition in SQLAlchemy core:

Column("created_at", DateTime(timezone=True), nullable=False)

Answer 8

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)

Answer 9

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)

Answer 10

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

Answer 11

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.

Answer 12

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.

Answer 13

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):

Answer 14

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)

Answer 15

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.

Answer 16

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