JSON

TL;DR

JSON (JavaScript Object Notation) is a popular data format used for representing structured data. It’s common to transmit and receive data between a server and web application in JSON format.

JSON in Python 3

Python has a built-in package called json, which can be used to work with JSON data.

import json

JSON to Python

You can parse a JSON string using json.loads() method. The method returns a dictionary.

For example:

import json

person = '{"name": "Bob", "languages": ["English", "Fench"]}' # JSON string
person_dict = json.loads(person) # Python dictionary

# Output: {'name': 'Bob', 'languages': ['English', 'Fench']}
print(person_dict)

# Output: ['English', 'French']
print(person_dict['languages'])

To read a file containing JSON object, you can use json.load() method

Suppose, you have a file named person.json which contains a JSON object.

{
    "name": "Bob", 
    "languages": [
        "English", 
        "Fench"
    ]
}

Parse this file:

import json

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

# Output: {'name': 'Bob', 'languages': ['English', 'Fench']}
print(data)

Json2Python Conversion table

Python to JSON

You can convert a dictionary to JSON string using json.dumps() method.

import json

person_dict = {
    'name': 'Bob',
    'age': 12,
    'children': None
}
person_json = json.dumps(person_dict)

# Output: {"name": "Bob", "age": 12, "children": null}
print(person_json)

To write JSON to a file in Python, we can use json.dump() method.

import json

person_dict = {
    "name": "Bob",
    "languages": [
        "English", 
        "Fench"
    ],
	"married": True,
	"age": 32
}

with open('person.json', 'w') as json_file:
  json.dump(person_dict, json_file)

When you run the program, the person.txt file will be created. The file has following text inside it.

{"name": "Bob", "languages": ["English", "Fench"], "married": true, "age": 32}

Python2Json Conversion table

Formatting

Indent

Use the indent parameter to define the numbers of indents. For example:

json.dumps(person_dict, indent=4)

Order the result

Sort keys in ascending order using sort_keys=True. E.g.:

json.dumps(person_dict, indent = 4, sort_keys=True)

Reference

• Python JSON

• Python JSON tutotials in w3schools

• Python3 JSON 数据解析