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import sqlite3
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from typing import Any, Iterable, List, Tuple, Optional, Dict
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class SQLiteDB:
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"""Thin wrapper around sqlite3 that exposes CRUD helpers."""
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def __init__(self, db_path: str = ":memory:") -> None:
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"""
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Open a connection to the SQLite database.
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Parameters
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----------
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db_path : str
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Path to the database file. Use ':memory:' for an in‑memory DB.
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"""
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self.db_path = db_path
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self.conn: sqlite3.Connection = sqlite3.connect(self.db_path)
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# Row factory makes rows behave like dictionaries
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self.conn.row_factory = sqlite3.Row
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self.cursor: sqlite3.Cursor = self.conn.cursor()
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# ------------------------------------------------------------------
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# Table helpers
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# ------------------------------------------------------------------
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def create_users_table(self) -> None:
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"""
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Create a simple 'users' table if it does not exist.
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Table schema:
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id INTEGER PRIMARY KEY AUTOINCREMENT
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name TEXT NOT NULL
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age INTEGER
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"""
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sql = """
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CREATE TABLE IF NOT EXISTS users (
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id INTEGER PRIMARY KEY AUTOINCREMENT,
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name TEXT NOT NULL,
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age INTEGER
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);
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"""
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self.cursor.execute(sql)
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self.conn.commit()
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# ------------------------------------------------------------------
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# CRUD
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# ------------------------------------------------------------------
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def insert_user(self, name: str, age: Optional[int] = None) -> int:
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"""
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Insert a new user.
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Returns
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-------
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int
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The newly created row id.
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"""
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sql = "INSERT INTO users (name, age) VALUES (?, ?)"
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self.cursor.execute(sql, (name, age))
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self.conn.commit()
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return self.cursor.lastrowid
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def get_user(self, user_id: int) -> Optional[Dict[str, Any]]:
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"""
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Retrieve a single user by id.
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Returns
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-------
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dict or None
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Row as a dictionary if found, otherwise None.
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"""
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sql = "SELECT * FROM users WHERE id = ?"
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self.cursor.execute(sql, (user_id,))
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row = self.cursor.fetchone()
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return dict(row) if row else None
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def get_all_users(self) -> List[Dict[str, Any]]:
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"""
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Retrieve all users.
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Returns
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-------
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list of dict
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All rows as dictionaries.
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"""
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sql = "SELECT * FROM users"
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self.cursor.execute(sql)
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rows = self.cursor.fetchall()
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return [dict(row) for row in rows]
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def update_user(self, user_id: int, name: Optional[str] = None,
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age: Optional[int] = None) -> bool:
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"""
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Update a user's name and/or age.
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Parameters
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----------
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user_id : int
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The id of the user to update.
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name : str | None
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New name (or None to leave unchanged).
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age : int | None
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New age (or None to leave unchanged).
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Returns
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-------
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bool
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True if a row was updated, False otherwise.
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"""
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# Build dynamic SET clause
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fields: List[str] = []
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values: List[Any] = []
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if name is not None:
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fields.append("name = ?")
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values.append(name)
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if age is not None:
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fields.append("age = ?")
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values.append(age)
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if not fields:
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# Nothing to update
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return False
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values.append(user_id)
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sql = f"UPDATE users SET {', '.join(fields)} WHERE id = ?"
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self.cursor.execute(sql, tuple(values))
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self.conn.commit()
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return self.cursor.rowcount > 0
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def delete_user(self, user_id: int) -> bool:
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"""
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Delete a user by id.
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Returns
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-------
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bool
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True if a row was deleted, False otherwise.
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"""
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sql = "DELETE FROM users WHERE id = ?"
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self.cursor.execute(sql, (user_id,))
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self.conn.commit()
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return self.cursor.rowcount > 0
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# ------------------------------------------------------------------
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# Utility
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# ------------------------------------------------------------------
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def close(self) -> None:
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"""Close the database connection."""
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self.cursor.close()
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self.conn.close()
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# Context manager support
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def __enter__(self) -> "SQLiteDB":
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return self
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def __exit__(self, exc_type, exc_val, exc_tb) -> None:
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self.close()
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