Merge/back_wzy/models/comment.py

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

class Comment(db.Model):
    __tablename__ = 'comments'

    id = db.Column(db.Integer, primary_key=True)
    post_id = db.Column(db.Integer, db.ForeignKey('posts.id', ondelete='CASCADE'), nullable=False)
    user_id = db.Column(db.Integer, db.ForeignKey('users.id', ondelete='CASCADE'), nullable=False)
    parent_id = db.Column(db.Integer, db.ForeignKey('comments.id', ondelete='CASCADE'))
    content = db.Column(db.Text, nullable=False)
    status = db.Column(db.Enum('active', 'deleted'), default='active', nullable=False)
    created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)
    updated_at = db.Column(db.DateTime, default=datetime.utcnow,
                           onupdate=datetime.utcnow, nullable=False)

    # self-referential replies
    replies = db.relationship(
        'Comment',
        backref=db.backref('parent', remote_side=[id]),
        lazy='dynamic',
        cascade='all, delete-orphan'
    )