Fix Python – Iterate over object attributes in python [duplicate]

Question

Asked By – Pablo Mescher

I have a python object with several attributes and methods. I want to iterate over object attributes.

class my_python_obj(object):
    attr1='a'
    attr2='b'
    attr3='c'

    def method1(self, etc, etc):
        #Statements

I want to generate a dictionary containing all of the objects attributes and their current values, but I want to do it in a dynamic way (so if later I add another attribute I don’t have to remember to update my function as well).

In php variables can be used as keys, but objects in python are unsuscriptable and if I use the dot notation for this it creates a new attribute with the name of my var, which is not my intent.

Just to make things clearer:

def to_dict(self):
    '''this is what I already have'''
    d={}
    d["attr1"]= self.attr1
    d["attr2"]= self.attr2
    d["attr3"]= self.attr3
    return d

ยท

def to_dict(self):
    '''this is what I want to do'''
    d={}
    for v in my_python_obj.attributes:
        d[v] = self.v
    return d

Update:
With attributes I mean only the variables of this object, not the methods.

Now we will see solution for issue: Iterate over object attributes in python [duplicate]


Answer

Assuming you have a class such as

>>> class Cls(object):
...     foo = 1
...     bar = 'hello'
...     def func(self):
...         return 'call me'
...
>>> obj = Cls()

calling dir on the object gives you back all the attributes of that object, including python special attributes. Although some object attributes are callable, such as methods.

>>> dir(obj)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'bar', 'foo', 'func']

You can always filter out the special methods by using a list comprehension.

>>> [a for a in dir(obj) if not a.startswith('__')]
['bar', 'foo', 'func']

or if you prefer map/filters.

>>> filter(lambda a: not a.startswith('__'), dir(obj))
['bar', 'foo', 'func']

If you want to filter out the methods, you can use the builtin callable as a check.

>>> [a for a in dir(obj) if not a.startswith('__') and not callable(getattr(obj, a))]
['bar', 'foo']

You could also inspect the difference between your class and its instance object using.

>>> set(dir(Cls)) - set(dir(object))
set(['__module__', 'bar', 'func', '__dict__', 'foo', '__weakref__'])

This question is answered By – Meitham

This answer is collected from stackoverflow and reviewed by FixPython community admins, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0