Flask-SQLAlchemy：sqlite3 IntegrityError

Question

我正在创建一个应用程序来替换浏览器中的当前选项卡管理器。我在组 - 表主题和选项卡 - 表选项卡之间创建了一个简单的一对多关系。如果我删除它，我希望能够自动删除主题的孩子。这是我目前拥有的：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()问题是当我尝试在数据库中添加某些内容时出现完整性错误，但我不确定会出现什么问题。如果我停止服务器，我还想将以前的记录保存在数据库中，我该如何实现？