如何在需要转换为JSON的Python对象中存储和访问日期时间

Question

我正在编写我的第一个python脚本，它创建和更新具有不同日期时间条目的对象。

我这样设置对象:

# Date conversion
import datetime
import time
# 0:01:00 and 0:00:00 threshold and totalseconds
threshold = time.strptime('00:01:00,000'.split(',')[0],'%H:%M:%S')
tick = datetime.timedelta(hours=threshold.tm_hour,minutes=threshold.tm_min,seconds=threshold.tm_sec).total_seconds()
zero_time = datetime.timedelta(hours=0,minutes=0,seconds=0)
zero_tick = zero_time.total_seconds()
format_date = '%d/%b/%Y:%H:%M:%S'
from datetime import datetime
# Response object
class ResponseObject(object):
    def __init__(self, dict):
      self.__dict__ = dict
# JSON encoding
from json import JSONEncoder
class MyEncoder(JSONEncoder):
    def default(self, o):
      return o.__dict__
# > check for JSON response object
try:
   obj
except NameError:
    obj = ResponseObject({})
...
entry = "14/Nov/2012:09:32:31 +0100"
entry_tz = str.join(' ', entry.split(None)[1:6])
entry_notz = entry.replace(' '+entry_tz,'')
this_time = datetime.strptime(entry_notz, format_date)
# > add machine to object if not there, add init time
if not hasattr(obj, "SOFTINST"):
    #line-breaks for readability
    setattr(obj, "SOFTINST", {  
        "init":this_time,
        "last":this_time,
        "downtime":zero_time,
        "totaltime":"",
        "percentile":100
    })
... 
print this_time
print MyEncoder().encode({"hello":"bar"})
print getattr(obj, "SOFTINST")

我的最后一个'print'返回这个:

{
  'totaltime': datetime.timedelta(0),
  'uptime': '',
  'last': datetime.datetime(2012, 11, 14, 9, 32, 31),
  'init': datetime.datetime(2012, 11, 14, 9, 32, 31),
  'percentile': 100, 
  'downtime': 0
}

我无法转换成JSON…

我不明白为什么:

print this_time   #2012-11-14 09:32:31

但是在对象内部，它被存储为

datetime.datetime(2012, 11, 14, 9, 32, 31)

问题:
我如何以"字符串格式"存储日期时间对象，并且仍然可以在Python中轻松访问(和修改)它们?

谢谢!

Answer 1

在datetime对象上使用isoformat方法。(参考:http://docs.python.org/release/2.5.2/lib/datetime-datetime.html)