app/db/models_chat.py

from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func

from app.db.database import Base


class ChatMessage(Base):
    __tablename__ = "chat_messages"

    id = Column(Integer, primary_key=True, index=True)

    user_id = Column(
        Integer,
        ForeignKey("user_accounts.id", ondelete="CASCADE"),
        nullable=False
    )

    # user OR assistant
    role = Column(String(20), nullable=False)

    content = Column(Text, nullable=False)

    created_at = Column(
        DateTime(timezone=True),
        server_default=func.now()
    )

    # relationship
    user = relationship("UserDB", back_populates="chats")