1

I am trying to check if the string entered by the user contains date using python.

something like this.

user_input = ("Enter date")
if user_input==#type of date(yyyy-mm-dd):
    print(okay)
else:
    print("failed")

2 Answers2

0

The dateutil library is your best friend when it comes to parsing dates:

>>> from dateutil.parser import *
>>> parse('2003-12-23')
datetime.datetime(2003, 12, 23, 0, 0)
>>> parse('2003-12-32')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "c:\srv\venv\dev\lib\site-packages\dateutil\parser\_parser.py", line 1356, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "c:\srv\venv\dev\lib\site-packages\dateutil\parser\_parser.py", line 653, in parse
    ret = self._build_naive(res, default)
  File "c:\srv\venv\dev\lib\site-packages\dateutil\parser\_parser.py", line 1227, in _build_naive
    naive = default.replace(**repl)
ValueError: day is out of range for month
>>>

If you want to be more restrictive, ie. only accept dates with the YYYY-MM-DD format, then checking with a regex first might be your thing:

def is_date(ds):
    if re.match(r'\d{4}-\d{2}-\d{2}', ds):
         return bool(parse(ds))
    return False

>>> is_date('2003-12-23')
True
>>> is_date('2003-12-32')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in is_date
  File "c:\srv\venv\dev\lib\site-packages\dateutil\parser\_parser.py", line 1356, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "c:\srv\venv\dev\lib\site-packages\dateutil\parser\_parser.py", line 653, in parse
    ret = self._build_naive(res, default)
  File "c:\srv\venv\dev\lib\site-packages\dateutil\parser\_parser.py", line 1227, in _build_naive
    naive = default.replace(**repl)
ValueError: day is out of range for month

If you don't want to be quite as restrictive, but accept all iso-formatted dates, then:

from dateutil.parser import isoparse
>>> isoparse('2003-12-23')
datetime.datetime(2003, 12, 23, 0, 0)
>>> isoparse('20031223')
datetime.datetime(2003, 12, 23, 0, 0)
thebjorn
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  • Generally yes, but it depends on whether you want to accept anything that looks like a valid date, or need to validate a date string in a specific format. – deceze May 05 '19 at 09:59
-1

This is what you want:

>>> import datetime
>>> def validate(date_text):
    try:
        datetime.datetime.strptime(date_text, '%Y-%m-%d')
    except ValueError:
        raise ValueError("Incorrect data format, should be YYYY-MM-DD")


>>> validate('2003-12-23')
>>> validate('2003-12-32')

Traceback (most recent call last):
  File "<pyshell#20>", line 1, in <module>
    validate('2003-12-32')
  File "<pyshell#18>", line 5, in validate
    raise ValueError("Incorrect data format, should be YYYY-MM-DD")
ValueError: Incorrect data format, should be YYYY-MM-DD
Iakovos Belonias
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