def _to_python(self, value, state):
"""Parse a string and return a datetime object."""
if value and isinstance(value, datetime):
return value
else:
try:
format = self.format
if callable(format):
format = format()
tpl = time.strptime(value, format)
except ValueError:
raise Invalid(self.message('badFormat', state), value, state)
# shoudn't use time.mktime() because it can give OverflowError,
# depending on the date (e.g. pre 1970) and underlying C library
return datetime(year=tpl.tm_year, month=tpl.tm_mon, day=tpl.tm_mday,
hour=tpl.tm_hour, minute=tpl.tm_min, second=tpl.tm_sec)
def _from_python(self, value, state):
"""Return a string representation of a datetime object."""
if not value:
return None
elif isinstance(value, datetime):
# Python stdlib can only handle dates with year greater than 1900
format = self.format
if callable(format):
format = format()
if format is None:
format = "%Y-%m-%d"
if value.year <= 1900:
return strftime_before1900(value, format)
else:
return value.strftime(format)
else:
return value