Python JSON Module

Python JSON Module: Streaming, Formatting, & Custom Objects

The json module allows custom serialization of complex domain models, fine-grained formatting control, and streaming execution.

Serialization Control Options

• indent: Specifier for pretty-printing (e.g. indent=2).
• sort_keys: Sort dictionary output keys alphabetically.
• separators: Compact encoding tuple e.g. (',', ':').

Practical Code Example

import json
from dataclasses import dataclass, asdict

@dataclass
class UserProfile:
    user_id: int
    username: str
    email: str

def json_advanced_demo() -> None:
    profile = UserProfile(101, "alex_dev", "[email protected]")

    # Serialize Dataclass using asdict()
    compact_json = json.dumps(asdict(profile), separators=(',', ':'))
    pretty_json = json.dumps(asdict(profile), indent=2, sort_keys=True)

    print("Compact JSON:", compact_json)
    print("
Pretty Formatted JSON:
", pretty_json)

if __name__ == "__main__":
    json_advanced_demo()

Best Practices & Gotchas

• Use asdict() for Dataclasses: Convert dataclasses to dictionaries with dataclasses.asdict() before passing to json.dumps().
• Use Compact Separators: For network APIs or caching, use separators=(',', ':') to minimize payload size.
• Handle UTF-8 Encoding: Set ensure_ascii=False in json.dumps() if preserving unicode characters (like non-English text or emojis).

Self-Check Challenge

Serialize a nested dictionary containing unicode characters using json.dumps(..., ensure_ascii=False, indent=2).