django1/django/utils/dateparse.py

94 lines
2.9 KiB
Python

"""Functions to parse datetime objects."""
# We're using regular expressions rather than time.strptime because:
# - they provide both validation and parsing,
# - they're more flexible for datetimes,
# - the date/datetime/time constructors produce friendlier error messages.
import datetime
import re
from django.utils.timezone import utc
from django.utils.tzinfo import FixedOffset
date_re = re.compile(
r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$'
)
datetime_re = re.compile(
r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
r'[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
r'(?P<tzinfo>Z|[+-]\d{1,2}:\d{1,2})?$'
)
time_re = re.compile(
r'(?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
)
def parse_date(value):
"""Parse a string and return a datetime.date.
Raise ValueError if the input is well formatted but not a valid date.
Return None if the input isn't well formatted.
"""
match = date_re.match(value)
if match:
kw = dict((k, int(v)) for k, v in match.groupdict().iteritems())
return datetime.date(**kw)
def parse_time(value):
"""Parse a string and return a datetime.time.
This function doesn't support time zone offsets.
Sub-microsecond precision is accepted, but ignored.
Raise ValueError if the input is well formatted but not a valid time.
Return None if the input isn't well formatted, in particular if it
contains an offset.
"""
match = time_re.match(value)
if match:
kw = match.groupdict()
if kw['microsecond']:
kw['microsecond'] = kw['microsecond'].ljust(6, '0')
kw = dict((k, int(v)) for k, v in kw.iteritems() if v is not None)
return datetime.time(**kw)
def parse_datetime(value):
"""Parse a string and return a datetime.datetime.
This function supports time zone offsets. When the input contains one,
the output uses an instance of FixedOffset as tzinfo.
Sub-microsecond precision is accepted, but ignored.
Raise ValueError if the input is well formatted but not a valid datetime.
Return None if the input isn't well formatted.
"""
match = datetime_re.match(value)
if match:
kw = match.groupdict()
if kw['microsecond']:
kw['microsecond'] = kw['microsecond'].ljust(6, '0')
tzinfo = kw.pop('tzinfo')
if tzinfo == 'Z':
tzinfo = utc
elif tzinfo is not None:
offset = 60 * int(tzinfo[1:3]) + int(tzinfo[4:6])
if tzinfo[0] == '-':
offset = -offset
tzinfo = FixedOffset(offset)
kw = dict((k, int(v)) for k, v in kw.iteritems() if v is not None)
kw['tzinfo'] = tzinfo
return datetime.datetime(**kw)