在Flask/ SQLAlchemy中更新一对多关系

from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50))
    posts = db.relationship('Post', backref='user', lazy=True)

class Post(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(100))
    content = db.Column(db.Text)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)

user = User.query.get(user_id)
post = Post.query.get(post_id)

post.user = user
user.posts.append(post)

post.user = None
user.posts.remove(post)

db.session.commit()