CODEWITHSUNDEEP
pythonsqlalchemy
Hubro
Hubro

Reputation: 59363

Can I add an event to a model in SQLAlchemy that fires when the item is deleted?

In my application, rows in the table "files" can be deleted in two ways. Either directly, like session.delete(file) or as the result of a cascade delete. I would like to delete the file from my file system, the file that the database row represents, when the row is deleted. Is there any way I can do that?

My model looks like this:

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):
        # ...

Upvotes: 2

Views: 177

Answers (1)

zifot
zifot

Reputation: 2688

Have you tried after_delete mapper event yet?

Upvotes: 1

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