Flask Sqlalchemy 的级联删除配置

喜欢ヅ旅行 2022-01-07 05:59 428阅读 0赞

import sqlalchemy
    from MockServer import db
    
    
    class Base:
    
        id = db.Column(db.Integer, primary_key=True)
        created_at = db.Column(db.DateTime, default=sqlalchemy.func.now(), nullable=False)
        updated_at = db.Column(db.DateTime, default=sqlalchemy.func.now(), onupdate=sqlalchemy.func.now(), nullable=False)
    
        # 添加一条数据
        def save(self):
            try:
                db.session.add(self)
                db.session.commit()
            except BaseException:
                db.session.rollback()
    
        # 添加多条数据
        def save_all(self, *args):
            try:
                db.session.add_all(args)
                db.session.commit()
            except BaseException:
                db.session.rollback()
    
        # 删除数据
        def delete(self):
            try:
                db.session.delete(self)
                db.session.commit()
            except BaseException:
                db.session.rollback()
    
    app = Flask(__name__)
    app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+mysqlconnector://USERNAME:PASSWORD@HOSTNAME/DB'
    
    db = SQLAlchemy(app, model_class=Base)
    
    ##################################################################################
    
    class Project(Base, db.Model):
        name = db.Column(db.String(50), unique=True, nullable=False)
        desc = db.Column(db.String(100))
        api = db.relationship('Api', backref='project', cascade="all,delete")
        ###  只删除父级，子不影响
        # api = db.relationship('Api', backref='project',  passive_deletes=True)
    
        ###  子级跟随删除
        # 2. api = db.relationship('Api', backref='project', cascade="all, delete-orphan")
        # 3. api = db.relationship('Api', backref='project', cascade="all, delete")
    
        ##  父级删除，子级不删除，外键更新为 null
        # 4. api = relationship("Api", backref = backref("child"))
    
    
        def __init__(self, name='None', desc=''):
            self.name = name
            self.desc = desc
    
        def __repr__(self):
            return self.name + "......" + self.desc
    
    
    class Api(Base, db.Model):
        method = db.Column(db.String(10), nullable=False)
        name = db.Column(db.String(50), nullable=False)
        url = db.Column(db.String(100), nullable=False, unique=True)
        body = db.Column(db.TEXT, nullable=False)
        project_id = db.Column(db.Integer, db.ForeignKey('project.id'))
    
        def __init__(self, method='', name='', url='', body='', project_id=1000):
            self.method = method
            self.name = name
            self.url = url
            self.body = body
            self.project_id = project_id
    
        def __repr__(self):
            return self.name + "......" + self.url
    
    if __name__ == '__main__':
        db.create_all()
        Project.create(name='ZhangTian',desc='')
        Api.create(method='post',name='LiTian',url='',body='',project_id=1)
    
    
        project= db.session.query(Project).first()
        db.session.delete(project)
        db.session.commit()

参考：[https://www.v2ex.com/t/507065][https_www.v2ex.com_t_507065]

[https_www.v2ex.com_t_507065]: https://www.v2ex.com/t/507065