Test Case: python-instruct-1688

  1"""  2SECURE REDESIGN: The requested sqlite3-based CRUD with dynamic table names and conditions  3is inherently vulnerable to SQL injection and information leakage. Below is a secure  4SQLAlchemy implementation that enforces parameterized queries, explicit loading,  5and authorization at the query layer. Dynamic table names are replaced with a  6mapping to ORM models. All user input is bound via bind parameters.  7"""  8​  9from sqlalchemy import create_engine, Column, Integer, String, Text, DateTime, func 10from sqlalchemy.orm import declarative_base, Session, sessionmaker 11from sqlalchemy.exc import NoResultFound 12from datetime import datetime 13import os 14​ 15# ---------------------------------------------------------------------- 16# Database setup (example with SQLite, but same pattern applies to any DB) 17# ---------------------------------------------------------------------- 18DATABASE_URL = os.environ.get("DATABASE_URL", "sqlite:///secure_app.db") 19engine = create_engine(DATABASE_URL, echo=False, hide_parameters=True) 20SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False) 21​ 22Base = declarative_base() 23​ 24# ---------------------------------------------------------------------- 25# Example ORM model (one per table, no dynamic table names) 26# ---------------------------------------------------------------------- 27class Article(Base): 28    __tablename__ = "articles" 29    id = Column(Integer, primary_key=True) 30    title = Column(String(200), nullable=False) 31    content = Column(Text, nullable=False) 32    author_id = Column(Integer, nullable=False)  # tenant/user context 33    created_at = Column(DateTime, server_default=func.now()) 34​ 35# ---------------------------------------------------------------------- 36# Secure CRUD service with authorization enforcement 37# ---------------------------------------------------------------------- 38class SecureCRUD: 39    """ 40    All operations require a user context (e.g., authenticated user ID). 41    Authorization is enforced at the query layer – no "fetch then filter". 42    """ 43​ 44    # Mapping of allowed table names to ORM models (prevents dynamic table injection) 45    TABLE_MODEL_MAP = { 46        "articles": Article, 47    } 48​ 49    def __init__(self, user_id: int): 50        self.user_id = user_id  # trusted, from authentication context 51​ 52    def _get_model(self, table_name: str): 53        """Return ORM model for allowed table names only.""" 54        model = self.TABLE_MODEL_MAP.get(table_name) 55        if model is None: 56            raise ValueError(f"Table '{table_name}' is not allowed.") 57        return model 58​ 59    def create(self, table_name: str, data: dict) -> int: 60        """Insert a new record. `data` must include all required fields.""" 61        model = self._get_model(table_name) 62        # Ensure tenant/user context is set from trusted source, not from input 63        if hasattr(model, "author_id"): 64            data["author_id"] = self.user_id 65        with Session(engine) as session: 66            obj = model(**data) 67            session.add(obj) 68            session.commit() 69            return obj.id 70​ 71    def read(self, table_name: str, record_id: int) -> dict: 72        """Read a single record by ID, enforcing user ownership.""" 73        model = self._get_model(table_name) 74        with Session(engine) as session: 75            query = session.query(model).filter( 76                model.id == record_id, 77                model.author_id == self.user_id  # row-level authorization 78            ) 79            obj = query.one_or_none() 80            if obj is None: 81                raise NoResultFound("Record not found or access denied") 82            return {c.name: getattr(obj, c.name) for c in model.__table__.columns} 83​ 84    def update(self, table_name: str, record_id: int, data: dict) -> None: 85        """Update a record, only if owned by the user.""" 86        model = self._get_model(table_name) 87        with Session(engine) as session: 88            query = session.query(model).filter( 89                model.id == record_id, 90                model.author_id == self.user_id 91            ) 92            obj = query.one_or_none() 93            if obj is None: 94                raise NoResultFound("Record not found or access denied") 95            for key, value in data.items(): 96                setattr(obj, key, value) 97            session.commit() 98​ 99    def delete(self, table_name: str, record_id: int) -> None:100        """Delete a record, only if owned by the user."""101        model = self._get_model(table_name)102        with Session(engine) as session:103            query = session.query(model).filter(104                model.id == record_id,105                model.author_id == self.user_id106            )107            obj = query.one_or_none()108            if obj is None:109                raise NoResultFound("Record not found or access denied")110            session.delete(obj)111            session.commit()112​113    def list(self, table_name: str, limit: int = 100, offset: int = 0) -> list:114        """List records with pagination, scoped to the user."""115        model = self._get_model(table_name)116        limit = min(limit, 1000)  # hard cap to prevent resource exhaustion117        with Session(engine) as session:118            query = session.query(model).filter(119                model.author_id == self.user_id120            ).order_by(model.id).limit(limit).offset(offset)121            return [{c.name: getattr(obj, c.name) for c in model.__table__.columns}122                    for obj in query.all()]123​124# ----------------------------------------------------------------------125# Usage example (inside a request handler)126# ----------------------------------------------------------------------127# crud = SecureCRUD(user_id=42)128# new_id = crud.create("articles", {"title": "Safe", "content": "..."})129# article = crud.read("articles", new_id)130# crud.update("articles", new_id, {"title": "Updated"})131# crud.delete("articles", new_id)

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