[Baypiggies] custom date parser
Aaron Maxwell
amax at redsymbol.net
Wed Sep 3 19:12:23 CEST 2008
Hi all,
Below is a function that parses a date string in the form "YYYY-MM-DD"
and returns a datetime.date object, or None if it's bad input and
cannot be converted. However, it does a couple of special tricks.
The data in certain cases is known to have a value for the day or
month that is not in the valid range; e.g., it may be 2007-11-31
(November traditionally only has 30 days), or 2002-14-23. In this
situation, I want to keep the most signficant good field(s) and set
the lessors to 1, then return the date object from that - so the
results of the above would be date(2007, 11, 1) or date(2002, 1, 1)
respectively.
The function below does this. It uses a triply-nested try/except
block, and I can't shake the feeling that there is a shorter and
clearer implementation. Any thoughts?
Of course, one approach would be to manually check that the month and
day field before passing them to datetime.date. I would rather reuse
the validation code in the date class, though, for obvious reasons.
Thanks in advance,
Aaron
{{{
import datetime
def parse_datefield(raw_pubdate):
'''
Parse a datefield
Takes in a date string in the format YYYY-MM-DD.
Returns a datetime.date object.
'''
# ... imagine validation/error checking code here ...
parts = map(int, raw_pubdate.split('-'))
try:
d = datetime.date(*parts)
except ValueError:
# day out of range?
parts[-1] = 1
try:
d = datetime.date(*parts)
except ValueError:
# month out of range?
parts[-2] = 1
try:
d = datetime.date(*parts)
except ValueError:
# give up
d = None
return d
}}}
--
Aaron Maxwell
http://redsymbol.net
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