Recursively convert python object graph to dictionary

Question

I\'m trying to convert the data from a simple object graph into a dictionary. I don\'t need type information or methods and I don\'t need to be able to convert it back to an

Answer 1

In Python there are many ways of making objects behave slightly differently, like metaclasses and whatnot, and it can override getattr and thereby have "magical" attributes you can't see through dict, etc. In short, it's unlikely that you are going to get a 100% complete picture in the generic case with whatever method you use.

Therefore, the answer is: If it works for you in the use case you have now, then the code is correct. ;-)

To make somewhat more generic code you could do something like this:

import types
def todict(obj):
    # Functions, methods and None have no further info of interest.
    if obj is None or isinstance(subobj, (types.FunctionType, types.MethodType))
        return obj

    try: # If it's an iterable, return all the contents
        return [todict(x) for x in iter(obj)]
    except TypeError:
        pass

    try: # If it's a dictionary, recurse over it:
        result = {}
        for key in obj:
            result[key] = todict(obj)
        return result
    except TypeError:
        pass

    # It's neither a list nor a dict, so it's a normal object.
    # Get everything from dir and __dict__. That should be most things we can get hold of.
    attrs = set(dir(obj))
    try:
        attrs.update(obj.__dict__.keys())
    except AttributeError:
        pass

    result = {}
    for attr in attrs:
        result[attr] = todict(getattr(obj, attr, None))
    return result            

Something like that. That code is untested, though. This still doesn't cover the case when you override getattr, and I'm sure there are many more cases that it doens't cover and may not be coverable. :)

Answer 2

A little update to Shabbyrobe's answer to make it work for namedtuples:

def obj2dict(obj, classkey=None):
    if isinstance(obj, dict):
        data = {}
        for (k, v) in obj.items():
            data[k] = obj2dict(v, classkey)
        return data
    elif hasattr(obj, "_asdict"):
        return obj2dict(obj._asdict())
    elif hasattr(obj, "_ast"):
        return obj2dict(obj._ast())
    elif hasattr(obj, "__iter__"):
        return [obj2dict(v, classkey) for v in obj]
    elif hasattr(obj, "__dict__"):
        data = dict([(key, obj2dict(value, classkey))
                     for key, value in obj.__dict__.iteritems()
                     if not callable(value) and not key.startswith('_')])
        if classkey is not None and hasattr(obj, "__class__"):
            data[classkey] = obj.__class__.__name__
        return data
    else:
        return obj

Answer 3

One line of code to convert an object to JSON recursively.

import json

def get_json(obj):
  return json.loads(
    json.dumps(obj, default=lambda o: getattr(o, '__dict__', str(o)))
  )

obj = SomeClass()
print("Json = ", get_json(obj))