Convert an RFC 3339 time to a standard Python time

问题:

Is there an easy way to convert an RFC 3339 time into a regular Python timestamp?

I've got a script which is reading an ATOM feed and I'd like to be able to compare the timestamp of an item in the ATOM feed to the modification time of a file.

I notice from the ATOM spec, that ATOM dates include a time zone offset (Z<a number>) but, in my case, there's nothing after the Z so I guess we can assume GMT.

I suppose I could parse the time with a regex of some sort but I was hoping Python had a built-in way of doing it that I just haven't been able to find.

回答1:

No builtin, afaik.

feed.date.rfc3339 This is a Python library module with functions for converting timestamp strings in RFC 3339 format to Python time float values, and vice versa. RFC 3339 is the timestamp format used by the Atom feed syndication format.

It is BSD-licensed.

http://home.blarg.net/~steveha/pyfeed.html

(Edited so it's clear I didn't write it. :-)

回答2:

You don't include an example, but if you don't have a Z-offset or timezone, and assuming you don't want durations but just the basic time, then maybe this will suit you:

import datetime as dt
>>> dt.datetime.strptime('1985-04-12T23:20:50.52', '%Y-%m-%dT%H:%M:%S.%f')
datetime.datetime(1985, 4, 12, 23, 20, 50, 520000)

The strptime() function was added to the datetime module in Python 2.5 so some people don't yet know it's there.

Edit: The time.strptime() function has existed for a while though, and works about the same to give you a struct_time value:

>>> ts = time.strptime('1985-04-12T23:20:50.52', '%Y-%m-%dT%H:%M:%S.%f')
>>> ts
time.struct_time(tm_year=1985, tm_mon=4, tm_mday=12, tm_hour=23, tm_min=20, tm_sec=50, tm_wday=4, tm_yday=102, tm_isdst=-1)
>>> time.mktime(ts)
482210450.0

回答3:

http://pypi.python.org/pypi/iso8601/ seems to be able to parse iso 8601, which RFC 3339 is a subset of, maybe this could be useful, but again, not built-in.

回答4:

http://bugs.python.org/issue15873 (duplicate of http://bugs.python.org/issue5207 )

Looks like there isn't a built-in as of yet.

回答5:

feedparser.py provides robust/extensible way to parse various date formats that may be encountered in real-world atom/rss feeds:

>>> from feedparser import _parse_date as parse_date
>>> parse_date('1985-04-12T23:20:50.52Z')
time.struct_time(tm_year=1985, tm_mon=4, tm_mday=12, tm_hour=23, tm_min=20,
                 tm_sec=50, tm_wday=4, tm_yday=102, tm_isdst=1)

回答6:

I struggled with RFC3339 datetime format a lot, but I found a suitable solution to convert date_string <=> datetime_object in both directions.

You need two different external modules, because one of them is is only able to do the conversion in one direction (unfortunately):

first install:

sudo pip install rfc3339
sudo pip install iso8601

then include:

import datetime     # for general datetime object handling
import rfc3339      # for date object -> date string
import iso8601      # for date string -> date object

For not needing to remember which module is for which direction, I wrote two simple helper functions:

def get_date_object(date_string):
  return iso8601.parse_date(date_string)

def get_date_string(date_object):
  return rfc3339.rfc3339(date_object)

which inside your code you can easily use like this:

input_string = '1989-01-01T00:18:07-05:00'
test_date = get_date_object(input_string)
# >>> datetime.datetime(1989, 1, 1, 0, 18, 7, tzinfo=<FixedOffset '-05:00' datetime.timedelta(-1, 68400)>)

test_string = get_date_string(test_date)
# >>> '1989-01-01T00:18:07-05:00'

test_string is input_string # >>> True

Heureka! Now you can easily (haha) use your date strings and date strings in a useable format.

回答7:

If you're using Django, you could use Django's function parse_datetime:

>>> from django.utils.dateparse import parse_datetime
>>> parse_datetime("2016-07-19T07:30:36+05:00")
datetime.datetime(2016, 7, 19, 7, 30, 36, tzinfo=<django.utils.timezone.FixedOffset object at 0x101c0c1d0>)

回答8:

Using Python 3, you can use RegEx to break the RFC 3339 timestamp into its components. Then, directly create the datetime object, no additional modules needed:

import re
import datetime

def parse_rfc3339(dt):
    broken = re.search(r'([0-9]{4})-([0-9]{2})-([0-9]{2})T([0-9]{2}):([0-9]{2}):([0-9]{2})(\.([0-9]+))?(Z|([+-][0-9]{2}):([0-9]{2}))', dt)
    return(datetime.datetime(
        year = int(broken.group(1)),
        month = int(broken.group(2)),
        day = int(broken.group(3)),
        hour = int(broken.group(4)),
        minute = int(broken.group(5)),
        second = int(broken.group(6)),
        microsecond = int(broken.group(8) or "0"),
        tzinfo = datetime.timezone(datetime.timedelta(
            hours = int(broken.group(10) or "0"),
            minutes = int(broken.group(11) or "0")))))

This example theads missing timezones or microseconds as "0" but might need additional error checking. Cheers, Alex

回答9:

try this, it works fine for me

datetime_obj =  datetime.strptime("2014-01-01T00:00:00Z", '%Y-%m-%dT%H:%M:%SZ')

or

datetime_obj = datetime.strptime("Mon, 01 Jun 2015 16:41:40 GMT", '%a, %d %b %Y %H:%M:%S GMT')

回答10:

rfc3339 library: http://henry.precheur.org/python/rfc3339

回答11:

Came across the awesome dateutil.parser module in another question, and tried it on my RFC3339 problem, and it appears to handle everything I throw at it with more sanity that any of the other responses in this question.