Python: 如何检查对象的类型是否为 datetime.date？

right way is

import datetime
isinstance(x, datetime.date)

When I try this on my machine it works fine. You need to look into why datetime.date is not a class. Are you perhaps masking it with something else? or not referencing it correctly for your import?

import datetime
d = datetime.date(2012, 9, 1)
print type(d) is datetime.date


> True

i believe the reason it is not working in your example is that you have imported datetime like so :

from datetime import datetime

this leads to the error you see

In [30]: isinstance(x, datetime.date)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
/<ipython-input-30-9a298ea6fce5> in <module>()
----> 1 isinstance(x, datetime.date)


TypeError: isinstance() arg 2 must be a class, type, or tuple of classes and types

if you simply import like so :

import datetime

the code will run as shown in all of the other answers

In [31]: import datetime


In [32]: isinstance(x, datetime.date)
Out[32]: True


In [33]:

If your existing code is already relying on from datetime import datetime, you can also simply also import date

from datetime import datetime, timedelta, date
print isinstance(datetime.today().date(), date)

In Python 3.5, isinstance(x, date) works to me:

>>> from datetime import date
>>> x = date(2012, 9, 1)
>>> type(x)
<class 'datetime.date'>
>>> isinstance(x, date)
True
>>> type(x) is date
True

According to documentation class date is a parent for class datetime. And isinstance() method will give you True in all cases. If you need to distinguish datetime from date you should check name of the class

import datetime


datetime.datetime.now().__class__.__name__ == 'date' #False
datetime.datetime.now().__class__.__name__ == 'datetime' #True
datetime.date.today().__class__.__name__ == 'date' #True
datetime.date.today().__class__.__name__ == 'datetime' #False

I've faced with this problem when i have different formatting rules for dates and dates with time

If you are using freezegun package in tests you may need to have more smart isinstance checks which works well with FakeDate and original Date/Datetime beeing inside with freeze_time context:

def isinstance_date(value):
"""Safe replacement for isinstance date which works smoothly also with Mocked freezetime"""
import datetime
if isinstance(value, datetime.date) and not isinstance(value, datetime.datetime):
return True
elif type(datetime.datetime.today().date()) == type(value):
return True
else:
return False




def isinstance_datetime(value):
"""Safe replacement for isinstance datetime which works smoothly also with Mocked freezetime """
import datetime
if isinstance(value, datetime.datetime):
return True
elif type(datetime.datetime.now()) == type(value):
return True
else:
return False

and tests to verify the implementation

class TestDateUtils(TestCase):


def setUp(self):
self.date_orig = datetime.date(2000, 10, 10)
self.datetime_orig = datetime.datetime(2000, 10, 10)


with freeze_time('2001-01-01'):
self.date_freezed = datetime.date(2002, 10, 10)
self.datetime_freezed = datetime.datetime(2002, 10, 10)


def test_isinstance_date(self):
def check():
self.assertTrue(isinstance_date(self.date_orig))
self.assertTrue(isinstance_date(self.date_freezed))
self.assertFalse(isinstance_date(self.datetime_orig))
self.assertFalse(isinstance_date(self.datetime_freezed))
self.assertFalse(isinstance_date(None))


check()
with freeze_time('2005-01-01'):
check()


def test_isinstance_datetime(self):
def check():
self.assertFalse(isinstance_datetime(self.date_orig))
self.assertFalse(isinstance_datetime(self.date_freezed))
self.assertTrue(isinstance_datetime(self.datetime_orig))
self.assertTrue(isinstance_datetime(self.datetime_freezed))
self.assertFalse(isinstance_datetime(None))


check()
with freeze_time('2005-01-01'):
check()

In Python 3.8.4 it can be checked that the method with isinstance will fail when checking if a datetime is whether a date or a datetime as both checks will give True.

    >>> from datetime import datetime, date
>>> mydatetime = datetime.now()
>>> mydate = mydatetime.date()
>>> isinstance(mydatetime, datetime)
True
>>> isinstance(mydatetime, date)
True

This is due to the fact that ABC0 is a subclass of date as it is explained in this other answer:

an instance of a derived class is an instance of a base class, too

Therefore, when distinguishing between datetime and date, type should be used instead:

    >>> type(mydatetime) == date
False
>>> type(mydate) == date
True
>>> type(mydate) == datetime
False
>>> type(mydatetime) == datetime
True