How can I add an item in a list from a JSON file in Python?

Question

I'm working with a JSON file and I was wondering if there's a way to append a string to a list within the file. Here's an example of the JSON file I'm working with:

{"language": "['English', 'French']", "bank": 50}

I want to add the string "Spanish" to the "language" list. How can I do this?

Here's the code I've written so far, but I'm not sure how to modify it to achieve what I want:

import json

with open("example.json", "r") as jsonFile:
    data = json.load(jsonFile)

add list(data["language"]['Spanish'])

with open("example.json", "w") as jsonFile:
    json.dump(data, jsonFile)

How can I modify this code to achieve my goal?

data["language"].append('Spanish'), then save back to your file. — 9769953
– 9769953, Commented Feb 13, 2023 at 14:46
Are you sure that the ['English', 'French'] in your file is surrounded by double quotes? Because that seems an awkward, probably bad, choice of JSON structure. It also invalidates my suggestion above. — 9769953
– 9769953, Commented Feb 13, 2023 at 14:49
Here is my json structure {"language": "['English', 'French']", "bank": 50} — BatteTarte
– BatteTarte, Commented Feb 13, 2023 at 14:56
Better to fix the input file to a more appropriate JSON format, then to fiddle around and doing weird things in code. — 9769953
– 9769953, Commented Feb 13, 2023 at 16:54

Peter Mortensen · Accepted Answer · 2023-02-18 17:41:39Z

2

{"language": "['English', 'French']", "bank": 50}

Here the "language" keys hold a string rather than a list because of the " before [ and " after ]. To solve this, change the file to this:

{"language": ["English", "French"], "bank": 50}

Then use this code to append "Spanish" or any language from now on:

import json

with open("temp.json", "r") as f:
    data = json.load(f)

data["language"].append("Spanish")

with open("temp.json", "w") as f:
    json.dump(data, f)

edited Feb 18, 2023 at 17:41

Peter Mortensen

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answered Feb 13, 2023 at 15:25

mind_uncapped

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Comments

Talha Tayyab · Accepted Answer · 2023-02-13 15:17:37Z

1

import json
import ast

with open("example.json", "r") as jsonFile:
    data = json.load(jsonFile)

#data={"language": "['English', 'French']", "bank": 50}

#take a variable e

e=ast.literal_eval(data['language'])

e.append('Spanish')

data['language']=e

print(data)
#{'language': ['English', 'French', 'Spanish'], 'bank': 50}

answered Feb 13, 2023 at 15:17

Talha Tayyab

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1 Comment

Peter Mortensen Over a year ago

An explanation would be in order. E.g., what did you change? What is the idea/gist? From the Help Center: "...always explain why the solution you're presenting is appropriate and how it works". Please respond by editing (changing) your answer, not here in comments (**** without **** "Edit:", "Update:", or similar - the answer should appear as if it was written today).

Peter Mortensen · Accepted Answer · 2023-02-18 16:25:31Z

0

In order to add to a Python list you should use the append() method.

Example:

import ast
ast.literal_eval(data["language"]).append("Spanish")

edited Feb 18, 2023 at 16:25

Peter Mortensen

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answered Feb 13, 2023 at 14:46

slqq

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7 Comments

BatteTarte Over a year ago

This give me an error: AttributeError: 'str' object has no attribute 'append'

9769953 Over a year ago

See my second comment to the question.

slqq Over a year ago

@BatteTarte if that's the case of list in double quotes you could: import ast ast.literal_eval(data["language"]).append("Spanish")

BatteTarte Over a year ago

This not work @slqq it just end the terminal and nothing happened

Peter Mortensen Over a year ago

literal_eval: "This is specifically designed not to execute Python code ... But it is not free from attack: A relatively small input can lead to memory exhaustion or to C stack exhaustion, crashing the process. There is also the possibility for excessive CPU consumption denial of service on some inputs. Calling it on untrusted data is thus not recommended."

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