Read and Write JSON to a file in Python

Published on June 5th, 2020

You can make use of the built-in json package in Python to read and write JSON data to a file.

Writing JSON to a file

You can store the information in a dictionary or dict object, which can contain any type of data like integers, booleans, arrays or nested objects.

By using a dict object, the json package will transform your dictionary into a serialized JSON string.

import json

dataObj = {}
dataObj['posts'] = []
    'title': 'Hello world',
    'category': 'Introduction',
    'slug': 'hello-world'

with open('data.json', 'w') as file:
    json.dump(dataObj, file)

Reading JSON from a file

Reading is as easy as writing to a file. Using the same package again, we can parse the JSON string directly from the file.

import json

with open('data.json', 'r') as file:
    data = json.load(file)
    for item in data['posts']:
        print 'Title: ' + item['title']
        print 'Category: ' + item['category']
        print 'Slug: ' + item['slug']

I read about different package alternatives like simplejson but I guess for now, this is a great way to get started especially, if you're working with web applications and are interacting with a serialized JSON data on a daily basis.