Question

I am using python-dateutil for parsing a date from a string:

import dateutil.parser
print dateutil.parser.parse('some null string', fuzzy=True).date()
2012-10-18
print dateutil.parser.parse('some 31 Oct 2012 string', fuzzy=True).date()
2012-10-31

What I am expecting is for dateutil.parser.parse('some null string', fuzzy=True).date() to throw an exception, but it’s returning the current date. Can someone show me how I can avoid getting the current date, if no date is found in the provided string?

Thanks in advance.

Answer 1

See the dateutil docs, specifically the parse function (emphasizes mine):

Additionally, the following keyword arguments are available:

default
If given, this must be a datetime instance. Any fields missing in the parsed date will be copied from this instance. The default value is the current date, at 00:00:00am.

… (snip) …

fuzzy
If fuzzy is set to True, unknown tokens in the string will be ignored.

Given that you’ve set fuzzy to True, no exception will be thrown as it will simply ignore all unknown tokens. And, as the default argument is not passed, the current date will be returned.

So the solution will be to either keep fuzzy set to False, so that invalid format strings will throw an exception; or check if the returned datetime is equal to the current date at 00:00:00am as an indication of a failed conversion.