backend/models/chat_memory.py

from sqlalchemy import Column, String, Text, DateTime, ForeignKey
from sqlalchemy.orm import relationship
from datetime import datetime
from core.database import Base

class Conversation(Base):
    __tablename__ = "conversations"

    id = Column(String, primary_key=True, index=True)
    user_id = Column(String, index=True)
    title = Column(String, default="New Chat")
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
    # Relationship to messages
    messages = relationship("Message", back_populates="conversation", cascade="all, delete-orphan")

class Message(Base):
    __tablename__ = "messages"

    id = Column(String, primary_key=True, index=True)
    conversation_id = Column(String, ForeignKey("conversations.id"))
    role = Column(String)  # 'user' or 'assistant'
    content = Column(Text)
    timestamp = Column(DateTime, default=datetime.utcnow)
    
    conversation = relationship("Conversation", back_populates="messages")