How to Convert Python Objects to JSON

JSON (JavaScript Object Notation) has become a standard format for exchanging data across applications due to its simplicity and compatibility with most programming languages. Python provides robust support for JSON through its built-in json module, making it straightforward to convert Python objects to JSON strings. In this guide, we’ll explore how to handle Python-to-JSON conversions efficiently and how to manage complex data structures.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based data format widely used for data exchange. It is platform-independent and supported by most programming languages. JSON is often used in:

• Web Applications: For transmitting data between servers and browsers.
• REST APIs: For exchanging structured data between systems.
• File Storage: To store configuration or structured data in .json files.

Common Features of JSON:

• Simple key-value pairs.
• Hierarchical structure with support for arrays and nested objects.
• Easily readable by both humans and machines.

JSON files typically use the .json extension.

Working with JSON in Python

Python’s json module offers powerful tools for encoding and decoding JSON. Start by importing the module:

import json

Converting Python Objects to JSON

1. Using json.dumps()

The json.dumps() method serializes Python objects (e.g., dictionaries, lists, and strings) into JSON-formatted strings.

Syntax:

json.dumps(obj, *, skipkeys=False, ensure_ascii=True, indent=None)

Example:

import json

data = {
    "name": "Dharmender",
    "age": 25,
    "is_student": False
}

json_string = json.dumps(data)
print(json_string)  # Output: {"name": "Dharmender", "age": 25, "is_student": false}

2. Pretty-Printing JSON Output

For human-readable JSON, use the indent parameter to format the output.

Example:

json_string = json.dumps(data, indent=4)
print(json_string)

Output:

{
    "name": "Dharmender",
    "age": 25,
    "is_student": false
}

3. Handling Non-Serializable Objects

By default, json.dumps() only supports Python’s basic types (e.g., dict, list, tuple, str, int, float, bool, and None). Non-serializable types (like custom objects) will raise a TypeError.

Solution:
Use the default parameter to define a custom serialization function or set skipkeys=True to ignore non-serializable keys.

Example with skipkeys:

data = {"name": "Dharmender", "age": 25, "address": object()}

json_string = json.dumps(data, skipkeys=True)
print(json_string)  # Output: {"name": "Alice", "age": 25}

Example with Custom Serialization:

class CustomObject:
    def __init__(self, value):
        self.value = value

def custom_encoder(obj):
    if isinstance(obj, CustomObject):
        return {"custom_value": obj.value}
    raise TypeError("Object not serializable")

data = {"custom": CustomObject(42)}
json_string = json.dumps(data, default=custom_encoder)
print(json_string)  # Output: {"custom": {"custom_value": 42}}

Converting Complex Python Objects to JSON

Example: Multiple Data Types

Python objects with various data types can be converted to JSON as long as the data types are supported.

Example:

data = {
    "name": "Amit",
    "scores": [85, 90, 78],
    "details": {"age": 22, "graduated": True},
    "hobbies": None
}

json_string = json.dumps(data, indent=2)
print(json_string)

Key Parameters for json.dumps()

Parameter	Description
indent	Specifies the indentation level for pretty-printing.
skipkeys	Skips keys that are not basic types like str, int, or None.
default	A custom function for serializing unsupported object types.
ensure_ascii	Ensures all non-ASCII characters are escaped (default: True).

Converting Python objects to JSON is straightforward with the json.dumps() method. Whether you’re working with basic types, pretty-printing JSON, or handling non-serializable objects, Python provides the tools you need to create structured and readable JSON output. Mastering these techniques will enhance your ability to work with APIs, file storage, and data serialization in Python.

Keep Learning 🙂