Change value of python nested dictionary with variable path?

Question

How can I pass a dictionary path as an argument? I thought maybe it had something to do with *args or **kwargs but I didn't understand how to use them for this

dictionary = {
    'key1': {
        'attribute1': 'green',
    },
    'attribute2': 5
}
def SaveToFile(target, value):
    with open('savefile.json', 'r') as savefile:
        dictionary = json.load(savefile)

    dictionary[target] = value

    with open('savefile.json', 'w') as savefile:
        json.dump(dictionary, savefile)

SaveToFile('["key1"]["attribute1"]', 'blue')
SaveToFile('["attribute2"]', 10)
print(dictionary)

desired output:

{
    'key1': {
        'attribute1': 'blue'
    },
    'attribute2': 10
}

stackoverflow.com/questions/47969721/… though why not just do ChangeValue(dictionary["key1"]["attribute1"], 'blue') and set that target equal to value? — Andrew Ryan
– Andrew Ryan, Commented Oct 30, 2022 at 8:20
@AndrewRyan I edited the question to better illustrate my needs. I don't have dictionary until the file is read so it can't be passed in the arguments — thelovedolphin
– thelovedolphin, Commented Oct 30, 2022 at 8:51

Deepak Tripathi · Accepted Answer · 2022-10-30 08:30:40Z

1

use regex and recursion to solve this

dictionary = {
    'key1': {
        'attribute1': 'green',
    },
    'attribute2': 5
}
import re

def update_dict(d_, val, *keys):
    if not keys:
        return {}
    key = keys[0]
    
    if isinstance(d_[key], dict):
        d_[key].update(update_dict(d_[key], val, *keys[1:]))
    else:
        if key in d_:
            d_[key]= val
    return d_
    

def ChangeValue(target, value):
    keys = filter(lambda x: bool(x), re.split('\[\"(.*?)\"\]', target))
    update_dict(dictionary, value, *keys)


ChangeValue('["key1"]["attribute1"]', 'blue')
ChangeValue('["attribute2"]', 10)
dictionary
# output {'key1': {'attribute1': 'blue'}, 'attribute2': 10}

answered Oct 30, 2022 at 8:30

Deepak Tripathi

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3 Comments

thelovedolphin Over a year ago

I updated my question to better illustrate my needs. Will this still work?

Deepak Tripathi Over a year ago

yes this will work, you can check

Deepak Tripathi Over a year ago

@thelovedolphin i will update my answer to accommodate this. You need to add sample example

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