Traverse JSON with nested property when index are in a list - python

Question

Is there a way to traverse a JSON when the index are in a list in Python.

JSON:

{
 "id" : "abc",
"Obj1":
    {
        "Obj1":{
             "Name" : "123456789"
             }
    }
}

Conventionally we can access JSON index as:

data['Obj1']['Obj1']['Name'] >>Output is 123456789

But how to traverse this and change the value in same 'data' json object if the index are in a list like:

['Obj1','Obj1','Name']

Need a way to traverse to the location by using list in place of hard code index.

I need to replace the value also with 'XYZ' so final json should be "{ "id" : "abc", "Obj1": { "Obj1":{ "Name" : "XYZ" } } }"

blhsing · Accepted Answer · 2018-10-21 15:43:25Z

1

You can use functools.reduce with dict.get:

from functools import reduce
path = ['Obj1','Obj1','Name']
print(reduce(lambda a, b: a[b], path, data))

This returns: 123456789

If you need to assign a new value 'XYZ' to the dict at the given path, you would then need to do it at a level above the leaf:

reduce(lambda a, b: a[b], path[:-1], data)[path[-1]] = 'XYZ'

edited Oct 21, 2018 at 15:43

answered Oct 21, 2018 at 13:37

blhsing

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5 Comments

user614946 Over a year ago

Thanks, but if i need to change the value in the original json object then?

blhsing Over a year ago

Not sure what you mean.. won't evaluating reduce(dict.get, path, data) again do?

user614946 Over a year ago

I mean from reduce I will get the value but I need to replace the value also with 'XYZ' so final json should be "{ "id" : "abc", "Obj1": { "Obj1":{ "Name" : "XYZ" } } }"

user614946 Over a year ago

Hi Just noticed if the element is an List this fails.

blhsing Over a year ago

I've updated my answer with a more general solution then.

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