A symmetric-python-datetime-json-codec

json_datetime.py

from time import mktime
from dateutil.parser import parse
from datetime import datetime
from json import JSONEncoder, JSONDecoder

ISOTIME_IDENTIFITER = '$isotime'
EPOCHTIME_IDENTIFIER = '$epochtime'

class JsonDatetimeEncoder(JSONEncoder):


    def default(self, obj):
        '''
        Encode datetimes both as an iso 8601 and unix timestamp (seconds from the epoch).
        
        >>> JsonDatetimeEncoder().encode(datetime(2012, 12, 30, 23, 29, 35, 579121))
        '{"$isotime": "2012-12-30T23:29:35.579121", "$epochtime": 1356902975.579121}'
        '''
        if isinstance(obj, datetime):
            return {ISOTIME_IDENTIFITER: obj.isoformat(),
                    EPOCHTIME_IDENTIFIER: mktime(obj.timetuple()) + obj.microsecond / 1e6}
        return super(JsonDatetimeEncoder, self).default(obj)

class JsonDatetimeDecoder(JSONDecoder):

    def __init__(self, **kwargs):
        super(JsonDatetimeDecoder, self).__init__(object_hook=self._datetime_object_hook, **kwargs)
    
    def _datetime_object_hook(self, obj):
        '''
        Decode an iso 8601 or a unix timestamp (seconds from the epoch).
        
        >>> JsonDatetimeDecoder().decode('{"$epochtime": 1356902975.579121}')
        datetime.datetime(2012, 12, 30, 23, 29, 35, 579121)

        >>> JsonDatetimeDecoder().decode('{"$isotime": "2012-12-30T23:29:35.579121"}')
        datetime.datetime(2012, 12, 30, 23, 29, 35, 579121)
        '''
        if isinstance(obj, dict):
            if ISOTIME_IDENTIFITER in obj:
                return parse(obj[ISOTIME_IDENTIFITER])
            elif EPOCHTIME_IDENTIFIER in obj:
                return datetime.fromtimestamp(obj[EPOCHTIME_IDENTIFIER])
        return obj