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, Flask

from flask_sqlalchemy import SQLAlchemy

from sqlalchemy import exc

from flask_whooshee import Whooshee

from datetime import datetime

app = Flask(__name__)

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'

app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

db = 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？