Read and write a valid Json file output in Python

Question

import json
import os
import shutil
import time
# import objectpath
import sys
import datetime
true = "true"
false = "false"
null = "null"

from datetime import datetime, timedelta


with open('./notificationsManagement/notifications.json') as json_file:
    data = json.load(json_file)


day_start = 30
for tuple in data:
    tuple['creationTime'] -=  int(timedelta(days = day_start).total_seconds())
    day_start -= 2

print(data)

text_file = open("output.json", "w")
text_file.write(str(data))
text_file.close()

I wrote a script in order to:

Read a Json File
Execute a modification
print the data
Output a new valid Json file as "output.json"

A few problem I encourted:

The Json's tuples are out of order
The data is printed with an 'u' before each header
The new file contains the same 'u' (Main problem)

Any suggestions?

The u in prefix indicates that it is a unicode. Check this link for more; stackoverflow.com/questions/2464959/… — Sumit S Chawla
– Sumit S Chawla, Commented Jan 16, 2019 at 12:04

Arount · Accepted Answer · 2019-01-16 12:19:45Z

About u'foo':

It's normal Python behavior, u'something' means your string is a Unicode string. see more about Unicode strings here

You can fix it simply by using this line to write your dict as JSON string, btw you should always use json.dump() (or json.dumps()) to write JSON string:

text_file.write(json.dump(data))

About keys order:

First, JSON's RFC is explicit about this:

An object is an unordered collection of zero or more name/value pairs, where a name is a string and a value is a string, number, boolean, null, object, or array.

Here, "object" means "hash", that's what we call "dictionnaries" with Python. That means keys of a JSON string are never ordered.

Moreover,

data = json.load(json_file) loads a JSON string and parse it to a Python dictionnary. Python dicts aren't ordered neither (at least before Python3.7).

This means two things:

You cannot read a JSON file in expected order.
According to point 1, it does not make sens to write a JSON string in a specific order (since you won't be able to read it in the same order)

r1024 · Accepted Answer · 2019-01-16 12:27:37Z

0

Regarding problem 2 & 3.

You should print it out without the Unicode output.

Reference here on writing JSON File.

How do I write JSON data to a file?

Regarding problem 3.:

If you would like ordering to be preserver you should use OrderedDict:

How to preserve ordering of items in a python dictionary?

answered Jan 16, 2019 at 12:27

r1024

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Comments

user10740899 · Accepted Answer · 2019-01-16 12:34:00Z

0

Are you sure that this is actually running ? (clean all .pyc)

Data is a dictonary and you iterate over the keys (strings) and treat them like a dict

for tuple in data:
    tuple['creationTime'] -=  int(timedelta(days = day_start).total_seconds())

answered Jan 16, 2019 at 12:34

user10740899

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