Error on refresh with UTCAttribute in python 2.7

[JohnCEarls]

A model that has a UTCDatetime attribute, if you do a model.refresh() you get the following error.

The problem is the attribute is a unicode object after being read and the function expects a datetime object. I doubt this is the right way to fix this bug, but it should give a place to start.

My setup
Python 2.7.3
delorean and six I believe were installed when Pynamodb was.

You have any trouble reproducing this, let me know.
something like

class myModel(Model):
    table_name = 'sometabel'                                                                           
    name = UnicodeAttribute( hash_key=True )                            
    date_created = UTCDateTimeAttribute( range_key=True, default=datetime.utcnow() )
    avar = UnicodeAttribute()

myModel.create_table( read_capacity_units=2, write_capacity_units=1, wait=True)
m = myModel('bar')
m.save()
models = [m for m in myModel.scan(name__eq='bar')]
models[0].refresh()

oughta reproduce it.

self._model.refresh()
File "/usr/local/lib/python2.7/dist-packages/pynamodb/models.py", line 360, in refresh
args, kwargs = self._get_save_args(attributes=False)
File "/usr/local/lib/python2.7/dist-packages/pynamodb/models.py", line 346, in _get_save_args
serialized = self.serialize(null_check=null_check)
File "/usr/local/lib/python2.7/dist-packages/pynamodb/models.py", line 391, in serialize
serialized = attr.serialize(value)
File "/usr/local/lib/python2.7/dist-packages/pynamodb/attributes.py", line 258, in serialize
fmt = Delorean(value, timezone=UTC).datetime.strftime(DATETIME_FORMAT)
File "/usr/local/lib/python2.7/dist-packages/delorean/dates.py", line 175, in init
if not is_datetime_naive(datetime):
File "/usr/local/lib/python2.7/dist-packages/delorean/dates.py", line 30, in is_datetime_naive
if dt.tzinfo is None:
AttributeError: 'unicode' object has no attribute 'tzinfo'

BTW, thanks for writing this. Been looking for something like this for a while now.

[jlafon]

The problem was that I wasn't deserializing object attributes that were also keys, so for unicode or string types everything worked, but failed with a key attribute that actually required serialization. Thanks for reporting this.