gistfile1.py

()>  app git:(master) ✗ ipython
Python 2.7.1 (r271:86832, Jul 31 2011, 19:30:53) 
Type "copyright", "credits" or "license" for more information.

IPython 0.13.1 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: import datetime

In [2]: import json

In [3]: json.dumps({'now': datetime.datetime.now()})
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-dbc125e49797> in <module>()
----> 1 json.dumps({'now': datetime.datetime.now()})

/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.pyc in dumps(obj, skipkeys, ensure_ascii, check_circular, allow_nan, cls, indent, separators, encoding, default, **kw)
    229         cls is None and indent is None and separators is None and
    230         encoding == 'utf-8' and default is None and not kw):
--> 231         return _default_encoder.encode(obj)
    232     if cls is None:
    233         cls = JSONEncoder

/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.pyc in encode(self, o)
    199         # exceptions aren't as detailed.  The list call should be roughly
    200         # equivalent to the PySequence_Fast that ''.join() would do.
--> 201         chunks = self.iterencode(o, _one_shot=True)
    202         if not isinstance(chunks, (list, tuple)):
    203             chunks = list(chunks)

/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.pyc in iterencode(self, o, _one_shot)
    262                 self.key_separator, self.item_separator, self.sort_keys,
    263                 self.skipkeys, _one_shot)
--> 264         return _iterencode(o, 0)
    265 
    266 def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,

/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.pyc in default(self, o)
    176 
    177         """
--> 178         raise TypeError(repr(o) + " is not JSON serializable")
    179 
    180     def encode(self, o):

TypeError: datetime.datetime(2012, 12, 8, 23, 49, 23, 47250) is not JSON serializable

In [4]: