python之我可以向 SQLAlchemy 中的模型添加一个事件，该事件会在删除项目时触发吗

在我的应用程序中，可以通过两种方式删除表“files”中的行。直接删除，如 session.delete(file) 或作为级联删除的结果。当删除行时，我想从我的文件系统中删除文件，即数据库行代表的文件。有什么办法可以做到吗？

我的模型是这样的:

class File(ModelBase): 
    """Model for the 'files' table. 
 
    This table holds data about uploaded files. 
    """ 
 
    __tablename__ = 'files' 
 
    # Columns 
    id = Column(INTEGER, primary_key=True) 
    uploaded_by_id = Column(INTEGER, ForeignKey(User.__tablename__ + '.id'), 
                            nullable=False) 
    path = Column(VARCHAR(255), nullable=False) # The file's name on the server 
    name = Column(VARCHAR(255), nullable=False) # The original file name 
    mime = Column(VARCHAR(75)) 
    size = Column(INTEGER, nullable=False)   # File size in bytes 
    uploaded_at = Column(DATETIME, nullable=False) 
 
    # Relationships 
    uploaded_by = relationship('User', backref='files_uploaded') 
 
    def __init__(self, uploaded_by, path, name): 
 
        with ProjectRootContext(): 
            self.uploaded_by = uploaded_by 
            self.path = path 
            self.name = name 
            self.mime = mimetypes.guess_type(path)[0] 
            self.size = os.path.getsize(path) 
            self.uploaded_at = datetime.now() 
 
    def __repr__(self): 
        return '<File(id=%s,name=%s)>' % (repr(self.id), repr(self.name)) 
 
    # Factory function for saving an uploaded file 
    @classmethod 
    def from_fieldstorage(cls, uploaded_by, fieldstorage): 
        # ... 

请您参考如下方法:

你试过了吗after_delete mapper event还没有？