Merge/back_wzy/models/topic.py

# models/topic.py
from extensions import db
from datetime import datetime

class Topic(db.Model):
    __tablename__ = 'topics'

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(100), unique=True, nullable=False)
    description = db.Column(db.Text)
    status = db.Column(db.Enum('active', 'archived'), default='active', nullable=False)
    created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)

    posts = db.relationship('Post', backref='topic', lazy='dynamic', cascade='all, delete')