How to append in a json file in Python?

Question

I have the a json file whose contents is {"67790": {"1": {"kwh": 319.4}}}. Now I create a dictionary a_dict which I need to append it into the json file. I tried the following but was not able to do it correctly. Where I'm going wrong?

with open(DATA_FILENAME, 'a') as f:    json_obj = json.dump(a_dict, json.load(f)    f.write(json_obj)    f.close() 

Answer 1

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.

Answer 2

You need to update the output of json.load with a_dict and then dump the result. And you cannot append to the file but you need to overwrite it.