Read, Write and Parse JSON using Python (original) (raw)

JSON is a lightweight data format for data interchange that can be easily read and written by humans and easily parsed and generated by machines. It is a complete language-independent text format. To work with JSON data, Python has a built-in package called JSON.

**Example:

s = '{"id":1, "name": "Emily", "language": ["C++", "Python"]}'

JSON Syntax

The syntax of JSON is a subset of **JavaScript's object notation and includes the following structural rules:

**Name/Value Pairs: Data is represented as key-value pairs. The key (or name) is a string followed by a colon (:), and each pair is separated by a comma (,).
**Curly Braces {}: Enclose JSON objects containing key-value pairs.
**Square Brackets []: Enclose arrays of values or objects.

Keys/Name must be strings with double quotes and values must be data types amongst the following:

String
Number
Object (JSON object)
array
Boolean
Null

**Example JSON file

{
"employee": [
{
"id": "1",
"name": "Amit",
"department": "Sales"
},
{
"id": "4",
"name": "Sunil",
"department": "HR"
}
]
}

Parsing JSON in Python

To convert a JSON string into a Python dictionary, use the json.loads() method from Python’s built-in json module.

Python `

import json emp = '{"id": "9", "name": "Nitin", "dept": "Finance"}' emp_dict = json.loads(emp)

print(emp_dict) print(emp_dict['name'])

Output

{'id': '9', 'name': 'Nitin', 'dept': 'Finance'} Nitin

Reading JSON from File

If you have JSON data stored in a .json file (for example, downloaded from an API or stored locally), Python's json module makes it easy to read and convert it into a Python dictionary using the json.load() function.

Assume the file data.json contains:

python-append-json1

**Example:

Python `

import json f = open('data.json',) data = json.load(f)

for i in data['emp_details']: print(i) f.close()

**Output:

python-read-json-output1

Convert Python Dictionary to JSON String

Python dictionaries can be easily converted to JSON strings using json.dumps(). This is useful when you want to send data over the network or store it in a text-based format.

Python `

import json

emp = { "id": "4", "name": "Sunil", "department": "HR" }

json_obj = json.dumps(emp, indent=4) print(json_obj)

Output

{ "id": "4", "name": "Sunil", "department": "HR" }

Python to JSON Data Type Conversion

Here's how Python's native types are converted to JSON equivalents:

Python	JSON Equivalent
dict	object
list, tuple	array
str	string
int, float	number
True	true
False	false
None	null

Writing JSON to a file in Python

Use json.dump() to write a Python dictionary to a JSON file. This is helpful for saving configuration, logs, user data or processed results.

Python `

import json

data = { "name": "Sathiyajith", "rollno": 56, "cgpa": 8.6, "phonenumber": "9976770500" }

with open("sample.json", "w") as outfile: json.dump(data, outfile)

**Output

python-json-write-to-file

Python Pretty Print JSON

When JSON is returned as a single line, it’s hard to read. You can pretty print JSON with indentation and sorted keys using the **json.dumps() function.

**Example:

Python `

import json

emp = '{"id":"9", "name": "Nitin", "department":"Finance"}' emp_d = json.loads(emp)

print(json.dumps(emp_d, indent=4, sort_keys=True))

Output

{ "department": "Finance", "id": "9", "name": "Nitin" }