Design a Data Helper for Beginners in Python

import json
from datetime import datetime
from pathlib import Path


class DataHelper:
    """A beginner-friendly helper for common data operations."""

    def __init__(self, data=None, filepath=None):
        self.data = data if data is not None else []
        self.filepath = Path(filepath) if filepath else None

    @classmethod
    def from_json(cls, filepath):
        """Load data from a JSON file."""
        with open(filepath, "r", encoding="utf-8") as f:
            payload = json.load(f)
        return cls(data=payload, filepath=filepath)

    def save_json(self, filepath=None):
        """Persist data as JSON atomically (write-temp-then-replace)."""
        target = Path(filepath) if filepath else self.filepath
        if not target:
            raise ValueError("No filepath provided")
        target.parent.mkdir(parents=True, exist_ok=True)
        tmp = target.with_suffix(".tmp")
        with open(tmp, "w", encoding="utf-8") as f:
            json.dump(self.data, f, indent=2)
        tmp.replace(target)
        return target

    def add_record(self, record):
        """Append a record with an automatic timestamp."""
        record = dict(record)
        record.setdefault("created_at", datetime.utcnow().isoformat())
        self.data.append(record)
        return record

    def summary(self):
        """Return a short summary of the dataset."""
        first = self.data[0] if self.data else {}
        return {
            "count": len(self.data),
            "keys": list(first.keys()) if isinstance(first, dict) else None,
        }


if __name__ == "__main__":
    helper = DataHelper()
    helper.add_record({"name": "Alice", "score": 42})
    helper.add_record({"name": "Bob", "score": 17})
    saved = helper.save_json("sample_data.json")
    reloaded = DataHelper.from_json(saved)
    print(json.dumps(reloaded.summary(), indent=2))