How to Create a Simple Data Helper in Python for LLM Projects

import json
from typing import Any, Dict, List, Optional


class DataHelper:
    """Simple helper for beginners to manage data in AI/LLM projects."""

    def __init__(self, data: Optional[List[Dict[str, Any]]] = None) -> None:
        self.data: List[Dict[str, Any]] = data or []

    def add_item(self, item: Dict[str, Any]) -> None:
        """Add a single data item."""
        self.data.append(item)

    def to_json(self, indent: int = 2) -> str:
        """Serialize data to JSON string (common LLM input format)."""
        return json.dumps(self.data, indent=indent)

    def filter_by(self, key: str, value: Any) -> List[Dict[str, Any]]:
        """Filter records by a key-value pair."""
        return [item for item in self.data if item.get(key) == value]

    def first_n(self, n: int) -> List[Dict[str, Any]]:
        """Get first n records — useful for prompt sampling."""
        return self.data[:n]


if __name__ == "__main__":
    helper = DataHelper()
    helper.add_item({"name": "Alice", "role": "user", "age": 30})
    helper.add_item({"name": "Bob", "role": "assistant", "age": 25})
    helper.add_item({"name": "Charlie", "role": "user", "age": 35})

    print("All data (JSON):")
    print(helper.to_json())

    print("\nFiltered role=user:")
    for rec in helper.filter_by("role", "user"):
        print(rec)

    print("\nFirst 2 records:")
    print(helper.first_n(2))