How to append to a JSON file in Python?

Assuming you have a test.json file with the following content:

{"67790": {"1": {"kwh": 319.4}}}

Then, the code below will load the json file, update the data inside using dict.update() and dump into the test.json file:

import json

a_dict = {'new_key': 'new_value'}

with open('test.json') as f:
    data = json.load(f)

data.update(a_dict)

with open('test.json', 'w') as f:
    json.dump(data, f)

Then, in test.json, you’ll have:

{"new_key": "new_value", "67790": {"1": {"kwh": 319.4}}}

Hope this is what you wanted.

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