how to convert a nested OrderedDict to dict?

Question

I have a nested OrderedDict I would like to convert to a dict. Applying dict() on it apparently only converts the outermost layer of the last entry.

from collections import OrderedDict

od = OrderedDict(
    [
        (u'name', u'Alice'),
        (u'ID', OrderedDict(
            [
                (u'type', u'card'),
                (u'nr', u'123')
            ]
        )),
        (u'name', u'Bob'),
        (u'ID', OrderedDict(
            [
                (u'type', u'passport'),
                (u'nr', u'567')
            ]
        ))
    ]
)

print(dict(od))

Output:

{u'name': u'Bob', u'ID': OrderedDict([(u'type', u'passport'), (u'nr', u'567')])}

Is there a direct method to convert all the occurences?

Answer 1

Simplest solution is to use json dumps and loads

from json import loads, dumps
from collections import OrderedDict

def to_dict(input_ordered_dict):
    return loads(dumps(input_ordered_dict))

NOTE: The above code will work for dictionaries that are known to json as serializable objects. The list of default object types can be found here

So, this should be enough if the ordered dictionary do not contain special values.

EDIT: Based on the comments, let us improve the above code. Let us say, the input_ordered_dict might contain custom class objects that cannot be serialized by json by default. In that scenario, we should use the default parameter of json.dumps with a custom serializer of ours.

(eg):

from collections import OrderedDict as odict
from json import loads, dumps

class Name(object):
    def __init__(self, name):
        name = name.split(" ", 1)
        self.first_name = name[0]
        self.last_name = name[-1]

a = odict()
a["thiru"] = Name("Mr Thiru")
a["wife"] = Name("Mrs Thiru")
a["type"] = "test" # This is by default serializable

def custom_serializer(obj):
    if isinstance(obj, Name):
        return obj.__dict__

b = dumps(a) 
# Produces TypeError, as the Name objects are not serializable
b = dumps(a, default=custom_serializer)
# Produces desired output

This example can be extended further to a lot bigger scope. We can even add filters or modify the value to our necessity. Just add an else part to the custom_serializer function

def custom_serializer(obj):
    if isinstance(obj, Name):
        return obj.__dict__
    else:
        # Will get into this if the value is not serializable by default 
        # and is not a Name class object
        return None

The function that is given at the top, in case of custom serializers, should be:

from json import loads, dumps
from collections import OrderedDict

def custom_serializer(obj):
    if isinstance(obj, Name):
        return obj.__dict__
    else:
        # Will get into this if the value is not serializable by default 
        # and is also not a Name class object
        return None

def to_dict(input_ordered_dict):
    return loads(dumps(input_ordered_dict, default=custom_serializer))

Answer 2

This should work:

import collections

def deep_convert_dict(layer):
    to_ret = layer
    if isinstance(layer, collections.OrderedDict):
        to_ret = dict(layer)

    try:
        for key, value in to_ret.items():
            to_ret[key] = deep_convert_dict(value)
    except AttributeError:
        pass

    return to_ret

Although, as jonrsharpe mentioned, there's probably no reason to do this -- an OrderedDict (by design) works wherever a dict does.