python json key became string not int

Question

So I have a data in json file which i never worked before.When I load and try print the data by index like print(data[0]) I got and warning

Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/app/extra/plugins/python/helpers/pydev/_pydev_bundle/pydev_umd.py", line 198, in runfile
    pydev_imports.execfile(filename, global_vars, local_vars)  # execute the script
  File "/app/extra/plugins/python/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "/home/levi/PycharmProjects/Topic-Modelling/main.py", line 37, in <module>
    print(data[0])
KeyError: 0

But When I print it like a print(data["0"]) the result as fine as expected.So I am confused the dict indexes change to string not integer.Can anyone tell me how to resolve this problem by change the keys into int.My code is like this


import json

def load_data(file):
    with open(file, "r", encoding="utf-8") as f:
        data = json.load(f)
    return data


def write_data(file, data):
    with open(file, "w", encoding="utf-8") as f:
        json.dump(data, f, indent=4)


data = load_data("file.json")["teks"]
print(data["0"])

Does this answer your question? [Using number as "index" (JSON)](https://stackoverflow.com/questions/8758715/using-number-as-index-json) — Behdad Abdollahi Moghadam, Oct 04 '21 at 04:39

score 3 · Accepted Answer · answered Oct 04 '21 at 04:19

3

This is expected behaviour. In JSON, object keys are always strings. The integer 0 is not a valid key. Integers are only valid for accessing JSON arrays.

answered Oct 04 '21 at 04:19

Anthony Manning-Franklin

4,408
1
18
23

so i little bit confused because of [this](https://www.youtube.com/watch?v=TKjjlp5_r7o&t=880s) at 8:00 he print the json by ```0``` which a int not a ```"0"``` like I did even i have the same code.Do you know a doc about that? – ddinfiwis Oct 04 '21 at 04:25
That is an array. If I have JSON `{"myArray": ["foo", "bar"]}` then I could access `data["myArray"][0]` in python and receive `"foo"`. However if I had JSON `{"myObject": {"property": "value", "0": "zero-keyed"}}` then of course accessing `data["myArray"][0]` would fail while `data["myArray"]["0"]` would succeed for the same reason that `data["myArray"]["property"]` would return `"value"`. – Anthony Manning-Franklin Oct 04 '21 at 09:56

score 2 · Answer 2 · answered Oct 04 '21 at 04:26

You can do the conversion of keys to int as part of your read function.

def load_data(file):
    with open(file, "r", encoding="utf-8") as f:
        data = json.load(f)
    return {int(k): v for k, v in data.items()}

When writing to the json file, json.dump() will still write the keys as strings for it to be valid json, but after reading from the file, you will be able to access data[0]

If you have some keys that are strings and some that are integers, you could try to convert to int, and in case an error occurs, skip the conversion.

def load_data(file):
    with open(file, "r", encoding="utf-8") as f:
        data = json.load(f)
    d = dict()
    for k, v in data.items():
        try:
            d[int(k)] = v
        except ValueError:
            d[k] = v
    return d

I got an error ```ValueError: invalid literal for int() with base 10: 'teks'``` and I really understand the error and the code — ddinfiwis, Oct 04 '21 at 05:25

python json key became string not int

2 Answers2