simple_model.py

from sqlalchemy import Column, ForeignKey, Integer, String
from sqlalchemy.orm import declarative_base, relationship

from fastapi_rowsecurity import Permissive, register_rls
from fastapi_rowsecurity.principals import Authenticated, UserOwner

Base = declarative_base()
register_rls(Base)


class User(Base):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True)
    username = Column(String, unique=True, index=True)
    items = relationship("Item", back_populates="owner")


class Item(Base):
    __tablename__ = "items"

    id = Column(Integer, primary_key=True)
    title = Column(String, index=True)
    owner_id = Column(Integer, ForeignKey("users.id"))
    owner = relationship("User", back_populates="items")

    __rls_policies__ = [
        Permissive(expr=Authenticated, cmd="SELECT"),
        Permissive(expr=UserOwner, cmd=["INSERT", "UPDATE", "DELETE"]),
    ]