Getting a dictionary from an object

Steven Bethard steven.bethard at gmail.com
Tue Jul 26 04:21:08 CEST 2005


Thanos Tsouanas wrote:
> On Sun, Jul 24, 2005 at 02:14:15PM -0600, Steven Bethard wrote:
> 
>>How about something like:
>>     dict((name, getattr(obj, name)) for name in dir(obj))
> 
> Pretty!!!
> 
>>Looks like this will get instance attributes, class attributes and 
>>properties just fine.
> 
> But not SQLObject's objects...
> Any idea why? (Getting attribute errors, it seems that these
> "attributoids" are not listed in dir(obj), so i have to use my ugly
> dictobj class.. :(

I don't know how SQLObjects are implemented, but I'm guessing they use 
__getattr__ or __getattribute__:

py> class C(object):
...     w = 1
...     @property
...     def x(self):
...         return 2
...     def __init__(self):
...         self.y = 3
...     def __getattr__(self, name):
...         if name == 'z':
...             return 4
...
py> c = C()
py> d = dict((name, getattr(c, name)) for name in dir(c))
py> d['w'], d['x'], d['y']
(1, 2, 3)
py> d['z']
Traceback (most recent call last):
   File "<interactive input>", line 1, in ?
KeyError: 'z'

Any attribute simulated through __getattr__ or __getattribute__ cannot 
be found by dir():

py> dir(c)
['__class__', '__delattr__', '__dict__', '__doc__', '__getattr__', 
'__getattribute__', '__hash__', '__init__', '__module__', '__new__', 
'__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', 
'__weakref__', 'w', 'x', 'y']

For this reason, I try to avoid implementing attributes through these 
methods, but sometimes it's unavoidable.

STeVe



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