json.dump doesn't dump anything, and leaves me with an empty file | Python

Question

I have been trying to dump a dictionary into my JSON file with the json library. However, when I dump, the file doesn't show anything inside it. Furthermore, when I read the file (using open('file').read()), it shows the data there! Can anyone help me locate this phantom data?

db = {'aaaa': 'bbbb'} # This is just for testing, but the shape of the actual DB will be about the same.

def write()
    while True:
        with open('C:\\Users\\very\\long\\path\\to\\json-file\\data.json', 'w') as f:
            
            json.dump(db, f)
            sleep(2)
            print('dumped')


Thread(target=write()).start()

Other info:
Environment: VSCode
Python version: 3.9.0
Library: json (import json)
Called: inside a thread.
No errors.

Answer 1

Correct code:

import json
from time import sleep
from threading import Thread
db = {'aaaa': 'bbbb'} 

def write():
    while True:
        with open('data2.json', 'w') as f:
            json.dump(db, f)
        print('dumped')
        sleep(10)


Thread(target=write()).start()

In your case, data is written (flushed) into the file and instantly file is reopened for writing. I have moved sleep from "with" statment and now it works