"""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
from django.utils.regex_helper import _lazy_re_compile
from django.utils.timezone import get_fixed_timezone
date_re = _lazy_re_compile(r"(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$")
time_re = _lazy_re_compile(
r"(?P<hour>\d{1,2}):(?P<minute>\d{1,2})"
r"(?::(?P<second>\d{1,2})(?:[.,](?P<microsecond>\d{1,6})\d{0,6})?)?$"
)
datetime_re = _lazy_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"\s*(?P<tzinfo>Z|[+-]\d{2}(?::?\d{2})?)?$"
)
standard_duration_re = _lazy_re_compile(
r"^"
r"(?:(?P<days>-?\d+) (days?, )?)?"
r"(?P<sign>-?)"
r"((?:(?P<hours>\d+):)(?=\d+:\d+))?"
r"(?:(?P<minutes>\d+):)?"
r"(?P<seconds>\d+)"
r"(?:[.,](?P<microseconds>\d{1,6})\d{0,6})?"
r"$"
)
# Support the sections of ISO 8601 date representation that are accepted by
# timedelta
iso8601_duration_re = _lazy_re_compile(
r"^(?P<sign>[-+]?)"
r"P"
r"(?:(?P<days>\d+([.,]\d+)?)D)?"
r"(?:T"
r"(?:(?P<hours>\d+([.,]\d+)?)H)?"
r"(?:(?P<minutes>\d+([.,]\d+)?)M)?"
r"(?:(?P<seconds>\d+([.,]\d+)?)S)?"
r")?"
r"$"
)
# Support PostgreSQL's day-time interval format, e.g. "3 days 04:05:06". The
# year-month and mixed intervals cannot be converted to a timedelta and thus
# aren't accepted.
postgres_interval_re = _lazy_re_compile(
r"^"
r"(?:(?P<days>-?\d+) (days? ?))?"
r"(?:(?P<sign>[-+])?"
r"(?P<hours>\d+):"
r"(?P<minutes>\d\d):"
r"(?P<seconds>\d\d)"
r"(?:\.(?P<microseconds>\d{1,6}))?"
r")?$"
)
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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.
"""
try:
return datetime.date.fromisoformat(value)
except ValueError:
if match := date_re.match(value):
kw = {k: int(v) for k, v in match.groupdict().items()}
return datetime.date(**kw)
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def parse_time(value):
"""Parse a string and return a datetime.time.
This function doesn't support time zone offsets.
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.
"""
try:
# The fromisoformat() method takes time zone info into account and
# returns a time with a tzinfo component, if possible. However, there
# are no circumstances where aware datetime.time objects make sense, so
# remove the time zone offset.
return datetime.time.fromisoformat(value).replace(tzinfo=None)
except ValueError:
if match := time_re.match(value):
kw = match.groupdict()
kw["microsecond"] = kw["microsecond"] and kw["microsecond"].ljust(6, "0")
kw = {k: int(v) for k, v in kw.items() if v is not None}
return datetime.time(**kw)
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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 a timezone with a fixed offset from UTC.
Raise ValueError if the input is well formatted but not a valid datetime.
Return None if the input isn't well formatted.
"""
try:
return datetime.datetime.fromisoformat(value)
except ValueError:
if match := datetime_re.match(value):
kw = match.groupdict()
kw["microsecond"] = kw["microsecond"] and kw["microsecond"].ljust(6, "0")
tzinfo = kw.pop("tzinfo")
if tzinfo == "Z":
tzinfo = datetime.timezone.utc
elif tzinfo is not None:
offset_mins = int(tzinfo[-2:]) if len(tzinfo) > 3 else 0
offset = 60 * int(tzinfo[1:3]) + offset_mins
if tzinfo[0] == "-":
offset = -offset
tzinfo = get_fixed_timezone(offset)
kw = {k: int(v) for k, v in kw.items() if v is not None}
return datetime.datetime(**kw, tzinfo=tzinfo)
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def parse_duration(value):
"""Parse a duration string and return a datetime.timedelta.
The preferred format for durations in Django is '%d %H:%M:%S.%f'.
Also supports ISO 8601 representation and PostgreSQL's day-time interval
format.
"""
match = (
standard_duration_re.match(value)
or iso8601_duration_re.match(value)
or postgres_interval_re.match(value)
)
if match:
kw = match.groupdict()
sign = -1 if kw.pop("sign", "+") == "-" else 1
if kw.get("microseconds"):
kw["microseconds"] = kw["microseconds"].ljust(6, "0")
kw = {k: float(v.replace(",", ".")) for k, v in kw.items() if v is not None}
days = datetime.timedelta(kw.pop("days", 0.0) or 0.0)
if match.re == iso8601_duration_re:
days *= sign
return days + sign * datetime.timedelta(**kw)
12月 18, 2023