`json`

The Python json module provides tools to encode and decode data in JavaScript Object Notation (JSON), a lightweight data interchange format that’s easy for humans to read and write and easy for machines to parse and generate.

Here’s a quick example:

Python
      
>>> import json
>>> # Convert a Python dictionary to a JSON string
>>> json.dumps({"name": "Alice", "age": 30})
'{"name": "Alice", "age": 30}'

Key Features

Serializes Python object to JSON strings
Deserializes JSON strings to Python objects
Supports complex data types with custom encoding and decoding

Frequently Used Classes and Functions

Object	Type	Description
`json.dump()`	Function	Serializes a Python object to a JSON-formatted stream
`json.dumps()`	Function	Serializes Python objects to a JSON-formatted string
`json.load()`	Function	Deserializes a JSON-formatted stream to a Python object
`json.loads()`	Function	Deserializes a JSON-formatted string to a Python object
`json.JSONEncoder`	Class	Provides a custom encoder for JSON serialization
`json.JSONDecoder`	Class	Provides a custom decoder for JSON deserialization

Examples

Serializing a Python dictionary to a JSON string:

Python
      
        
      
    
>>> import json
>>> data = {"name": "Bob", "age": 25}
>>> json_str = json.dumps(data)
>>> json_str
'{"name": "Bob", "age": 25}'

Deserializing a JSON string to a Python dictionary:

Python
      
>>> json.loads('{"name": "Bob", "age": 25}')
{'name': 'Bob', 'age': 25}

Serializing with pretty printing:

Python
      
        
      
    
>>> print(json.dumps(data, indent=2))
{
  "name": "Bob",
  "age": 25
}

Common Use Cases

Storing and exchanging data between a web server and a client
Configuring applications with JSON files
Logging structured data in a human-readable format

Real-World Example

You can use the json module to read configuration data from a JSON file and update it programmatically. Here’s an example of updating a user’s profile information stored in a JSON file:

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>>> import json
>>> import pathlib
>>> config_file = pathlib.Path("user_config.json")

>>> # Read the existing configuration
>>> with config_file.open(mode="r", encoding="utf-8") as file:
...     config = json.load(file)
...

>>> # Update user profile information
>>> config["user"]["name"] = "Charlie"
>>> config["user"]["preferences"]["theme"] = "dark"

>>> # Write the updated configuration back to the file
>>> with config_file.open(mode="w", encoding="utf-8") as file:
...     json.dump(config, file, indent=4)
...

>>> # Verify the file update
>>> with config_file.open("r") as file:
...     updated_config = json.load(file)
...

>>> updated_config["user"]["name"]
'Charlie'

This example demonstrates how you can use the json module to read, modify, and write JSON data to a file, facilitating tasks such as application configuration management.

Tutorial

Working With JSON Data in Python

Learn how to work with JSON data in Python using the json module. Convert, read, write, and validate JSON files and handle JSON data for APIs and storage.

intermediate python

For additional information on related topics, take a look at the following resources: