from uuid import uuid4 from datetime import datetime, timezone from sqlalchemy import Column, String, DateTime, UUID from cognee.infrastructure.databases.relational import Base class Principal(Base): __tablename__ = "principals" id = Column(UUID, primary_key=True, index=True, default=uuid4) created_at = Column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)) updated_at = Column(DateTime(timezone=True), onupdate=lambda: datetime.now(timezone.utc)) type = Column(String, nullable=False) __mapper_args__ = { "polymorphic_identity": "principal", "polymorphic_on": "type", }