How to Log Errors with Structured Fields in Python

import logging
import sys

def log_structured_error(operation: str, user_id: int, status_code: int, error_msg: str):
    """Log an error with structured fields using a dictionary."""
    logger = logging.getLogger("structured_logger")
    logger.setLevel(logging.ERROR)
    
    # Create console handler if not already present
    if not logger.handlers:
        handler = logging.StreamHandler(sys.stdout)
        handler.setFormatter(logging.Formatter("%(message)s"))
        logger.addHandler(handler)
    
    structured_data = {
        "operation": operation,
        "user_id": user_id,
        "status_code": status_code,
        "error": error_msg,
    }
    logger.error("Operation failed: %s", operation, extra={"structured": structured_data})

if __name__ == "__main__":
    log_structured_error("checkout", 12345, 500, "Database connection timeout")
    log_structured_error("login", 67890, 401, "Invalid credentials")