type object 'datetime.datetime' has no attribute 'fromisoformat'

Question

I have a script with the following import:

from datetime import datetime

and a piece of code where I call:

datetime.fromisoformat(duedate)

Sadly, when I run the script with an instance of Python 3.6, the console returns the following error:

AttributeError: type object 'datetime.datetime' has no attribute 'fromisoformat'

I tried to run it from two instances of anaconda (3.7 and 3.8) and it works nice and smooth. I supposed there was an import problem so I tried to copy datetime.py from anaconda/Lib to the script directory, with no success.

The datetime.py clearly contains the class datetime and the method fromisoformat but still it seems unlinked. I even tried to explicitly link the datetime.py file, with the same error:

parent_dir = os.path.abspath(os.path.dirname(__file__))
vendor_dir = os.path.join(parent_dir, 'libs')
sys.path.append(vendor_dir+os.path.sep+"datetime.py")

Can you help me? My ideas are over...

Dissipation

Answer 1

The issue here is actually that fromisoformat is not available in Python versions older than 3.7, you can see that clearly stated in the documenation here.

Return a date corresponding to a date_string given in the format YYYY-MM-DD:
>>>

>>> from datetime import date
>>> date.fromisoformat('2019-12-04')
datetime.date(2019, 12, 4)

This is the inverse of date.isoformat(). It only supports the format YYYY-MM-DD.

New in version 3.7.

Draughts

doh... do you know an alternative for older python 3's instances? – Dissipation

perhaps this is what you are looking for – Draughts

isoformat() seems to have the opposite effect since it translates to ISO8601 format. I'll look for alternative solutions. Thanks btw – Dissipation

Answer 2

I had the same issue and found this:

https://pypi.org/project/backports-datetime-fromisoformat/

>>> from datetime import date, datetime, time
>>> from backports.datetime_fromisoformat import MonkeyPatch
>>> MonkeyPatch.patch_fromisoformat()

>>> datetime.fromisoformat("2014-01-09T21:48:00-05:30")
datetime.datetime(2014, 1, 9, 21, 48, tzinfo=-05:30)

>>> date.fromisoformat("2014-01-09")
datetime.date(2014, 1, 9)

>>> time.fromisoformat("21:48:00-05:30")
datetime.time(21, 48, tzinfo=-05:30)

Works like a charm.

Jimjams

Works great, but is there a function like timedelta in datetime.datetime. How can you increment the date here ? – Rosary

It works just like you would expect. Since you still import datetime and just update the fromisoformat the rest stays unchanged. – Jimjams

Answer 3

You should refactor datetime.fromisoformat('2021-08-12') to use datetime.strptime like this:

In [1]: from datetime import datetime                                                                                                                                                          

In [2]: datetime.strptime("2021-08-08", "%Y-%m-%d")                                                                                                                                           
Out[2]: datetime.datetime(2021, 8, 8, 0, 0)

Immutable

Answer 4

Python version 3.6 and older don't have the fromisoformat() methods - as mentioned in other documentation - both datetime.fromisoformat (docs) and date.fromisoformat (docs) are not available.

You can use this code I wrote to implement this in Python 3.6. I prefer not to install additional dependencies for functions I hardly use - in my case, I only use it in a test.

Python3.6 and below

from datetime import datetime

time_expected = datetime.now()
time_actual = datetime.strptime(time_actual.isoformat(), "%Y-%m-%dT%H:%M:%S.%f")
assert time_actual == time_expected

Python3.7+

from datetime import datetime

time_expected = datetime.now()
time_actual = datetime.fromisoformat(time_expected.isoformat())
assert time_actual == time_expected

Phosphorescence

Answer 5

I ran into this problem, or the same error message, anyway, even though I am running Python 3.11.6. In my case, the real issue is confusion over the import name and the class name. To wit:

(venv) rob@robuntuflex:~/proj/pracMonFront$ python Python 3.11.6 (main, Oct 8 2023, 05:06:43) [GCC 13.2.0] on linux Type "help", "copyright", "credits" or "license" for more information.

>>> import datetime >>> datetime.fromisoformat("2023-10-07T10:20:38") Traceback (most recent call last): File "", line 1, in AttributeError: module 'datetime' has no attribute 'fromisoformat' >>> datetime.datetime.fromisoformat("2023-10-07T10:20:38") datetime.datetime(2023, 10, 7, 10, 20, 38)

HTH

/rob

Bustard