我正在創(chuàng)建一個應用程序來替換瀏覽器中的當前選項卡管理器。我在組 - 表主題和選項卡 - 表選項卡之間創(chuàng)建了一個簡單的一對多關(guān)系。如果我刪除它，我希望能夠自動刪除主題的孩子。這是我目前擁有的：from flask import request, redirect, url_for, render_template, Flaskfrom flask_sqlalchemy import SQLAlchemyfrom sqlalchemy import excfrom flask_whooshee import Whoosheefrom datetime import datetimeapp = Flask(__name__)app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = Falsedb = SQLAlchemy(app)whooshee = Whooshee(app)@whooshee.register_model('topic_name')class Topic(db.Model):    __tablename__ = 'topic'    id = db.Column(db.Integer, primary_key=True, autoincrement=True)    topic_name = db.Column(db.String, unique=True, nullable=False)    topic_created = db.Column(db.DateTime, default=datetime.utcnow)    topic_changed = db.Column(db.DateTime, default=datetime.utcnow)    topic_tabs = db.relationship('Tab', backref='topic', cascade='all, delete-orphan', lazy='dynamic')@whooshee.register_model('tab_name', 'tab_link', 'tab_description')class Tab(db.Model):    __tablename__ = 'tab'    id = db.Column(db.Integer, primary_key=True, autoincrement=True)    tab_name = db.Column(db.String, nullable=False)    tab_link = db.Column(db.String, unique=True, nullable=False)    tab_favicon = db.Column(db.String)    tab_description = db.Column(db.String)    tab_created = db.Column(db.DateTime, default=datetime.utcnow)    tab_changed = db.Column(db.DateTime, default=datetime.utcnow)    topic_id = db.Column(db.Integer, db.ForeignKey('topic.id'))@app.route('/', methods=['GET'])def index():    return "Test"if __name__ == '__main__':    db.create_all()    try:        db.session.commit()    except exc.IntegrityError as e:        print(str(e))        db.session.rollback()    top = Topic(topic_name='Test')    db.session.add(top)    try:        db.session.commit()    except exc.IntegrityError as e:        print(str(e))        db.session.rollback()問題是當我嘗試在數(shù)據(jù)庫中添加某些內(nèi)容時出現(xiàn)完整性錯誤，但我不確定會出現(xiàn)什么問題。如果我停止服務器，我還想將以前的記錄保存在數(shù)據(jù)庫中，我該如何實現(xiàn)？