How to Load and Save CSV and JSON Files in Python

from pathlib import Path
import json
import csv


def load_data(file_path):
    """Load CSV or JSON data from disk based on file extension."""
    path = Path(file_path)
    if path.suffix == ".json":
        with path.open() as f:
            return json.load(f)
    elif path.suffix == ".csv":
        with path.open(newline="") as f:
            return list(csv.DictReader(f))
    else:
        raise ValueError(f"Unsupported file type: {path.suffix}")


def save_data(file_path, data):
    """Save data to CSV or JSON file based on file extension."""
    path = Path(file_path)
    path.parent.mkdir(parents=True, exist_ok=True)
    if path.suffix == ".json":
        with path.open("w") as f:
            json.dump(data, f, indent=2)
    elif path.suffix == ".csv":
        if not data:
            raise ValueError("Cannot write empty list to CSV")
        fieldnames = data[0].keys()
        with path.open("w", newline="") as f:
            writer = csv.DictWriter(f, fieldnames=fieldnames)
            writer.writeheader()
            writer.writerows(data)
    else:
        raise ValueError(f"Unsupported file type: {path.suffix}")


if __name__ == "__main__":
    sample_data = [{"name": "Alice", "age": 30}, {"name": "Bob", "age": 25}]
    save_data("output/people.json", sample_data)
    loaded = load_data("output/people.json")
    print(loaded)