Iterating over a .json file and changing a attribute value

Question

I'm trying to iterate over a .json file with a small script to find a attribute named 'model' and change it's value on each object. (It's a db-dump from Django).

import codecs, json

data = ""

with codecs.open("dump2.json", 'r', 'utf8') as data_file:    
    data = json.load(data_file)

for i in data:
    for key in i:
        if key[0] == 'model':
            key[1] = "app.model" #not working

with codecs.open('dump2.json', 'w', 'utf8') as f:
    json.dump(data, f)

What am I doing wrong here? I don't get any errors. And values are not changed.

Anand, I dont think it's anything wrong with the json. It's a file generated from djangos 'dumpdata' command and it works when printing key[1] just not when assigning the new value. — user3199840
– user3199840, Commented Aug 16, 2015 at 18:06
Well unless you provide an example of your json, that works with your code , we would have no idea what data or i or key or anything else for that matter is? How do you think we would be able to advice what is going wrong? — Anand S Kumar
– Anand S Kumar, Commented Aug 16, 2015 at 18:07
@user3199840, Even if there is no problem with the json itself, it is much easier to help knowing what is making yout trouble. Otherwise advises would be based only on guesses — André Teixeira
– André Teixeira, Commented Aug 16, 2015 at 18:08
Ok. I'll be back with further documentation on whats going on here. — user3199840
– user3199840, Commented Aug 16, 2015 at 18:25

unutbu · Accepted Answer · 2015-08-16 19:19:08Z

3

Based on some random documentation I found on the web. I assume you have such a json structure:

[
    {

        "pk": 1,
        "model": "auth.user",
        "fields":{
            "username": "test1"
        }
    },{
        "pk": 2,
        "model": "auth.user",
        "fields":{
            "username": "test2"
        }
    }
]

Using this json as example, when your code executes it iterates correctly over json keys on the line for i in data:. But on the second loop for key in i:, you are iterating over a string ("model" string). So, in this case, key[0] is 'm', key[1] is 'o' and so on...

You should try this way:

import codecs, json

data = ""

with codecs.open("dump2.json", 'r', 'utf8') as data_file:    
    data = json.load(data_file)

for i in data:
    for key in i:
        if key=="model":
            i[key] = "app.model"

with codecs.open('dump2.json', 'w', 'utf8') as f:
    json.dump(data, f)

edited Aug 16, 2015 at 19:19

unutbu

886k197 gold badges1.9k silver badges1.7k bronze badges

answered Aug 16, 2015 at 18:40

André Teixeira

2,6124 gold badges30 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Iterating over a .json file and changing a attribute value

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related