Access all keys including lists in JSON using Python

Question

I would like to access all the keys including within lists in a JSON document and modify them.

I have the following code, but this just prints the top level keys:

#!/usr/bin/env python3

import json

file = 'example.json'
f = open(file)
data = json.load(f)

for key, value in data.items():
        print(key)

Thus, for the JSON document:

{
"a":1,
"b":2,
"c":[
     {
     "d":4,
     "e":5,
     "f":{
         "g":6
         }
     }
    ]
}

I just get the output:

a
b
c

whereas I want to access and amend all the keys, namely:

a
b
c
d
e
f
g

Note that c is a list, which hides d e f g.

You need a recursive approach here.

Jan
– Jan

2021-11-04 13:26:59 +00:00
Commented Nov 4, 2021 at 13:26 — Jan
– Jan, Commented Nov 4, 2021 at 13:26

user2390182 · Accepted Answer · 2021-11-04 15:52:27Z

3

You will need some sort of recursion to traverse the data:

def nested_keys(obj):
    if isinstance(obj, dict):
        for k, v in obj.items():
            yield k
            yield from nested_keys(v)
    elif isinstance(obj, list):
        for sub in obj:
            yield from nested_keys(sub)

>>> [*nested_keys(data)]
['a', 'b', 'c', 'd', 'e', 'f', 'g']

To rename keys:

def rename_keys(obj, mapping):
    if isinstance(obj, dict):
        return {mapping[k]: rename_keys(v, mapping) for k, v in obj.items()}
    if isinstance(obj, list):
        return [rename_keys(sub, mapping) for sub in obj]
    return obj

rename_keys(data, dict("a1 b2 c3 d4 e5 f6 g6".split()))
# {'1': 1, '2': 2, '3': [{'4': 4, '5': 5, '6': {'6': 6}}]}

edited Nov 4, 2021 at 15:52

answered Nov 4, 2021 at 13:27

user2390182

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8 Comments

Jan Over a year ago

Plus one - problem is that you possibly cannot do anything with the nested keys (one is not able to get the value with the key names alone, that is).

NetHead Over a year ago

Thanks @user2390182, that prints out all the keys. How would I change the key names? I have tried defining a new global dictionary data2 = { } and adding data2[k + '0'] = obj[k] after the for k, v in obj.items: line, but the result is data2 = {'a0': 1, 'b0': 2, 'c0': [{'d': 4, 'e': 5, 'f': {'g': 6}}], 'd0': 4, 'e0': 5, 'f0': {'g': 6}, 'g0': 6}. That is, the new keys have been added to the list, but the old keys have not been deleted.

user2390182 Over a year ago

Can you provide some hints with regard to the logic of the renaming

NetHead Over a year ago

I have a Python dictionary with old key names and new key names. Ideally I want to replace the key names in situ, but I could also create a new JSON document from the existing JSON document.

user2390182 Over a year ago

Added an example to create a new dict with keys replaced by their substitute taken from a mapping.

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