Flush Error while deleting data using sqlalchemy

Question

I have following two schema.

class Stop(Base):
    '''
        Class Model for Stops
    '''
    __tablename__ = 'STOPS'
    uid = Column('uid', Integer, primary_key=True, autoincrement=False)
    category_code = Column('category_code', String(60), nullable=False)

and

class StopName(Base):
    '''
        Class Model for StopNames
    '''
    __tablename__ = 'STOP_NAME'
    uid = Column('uid', Integer, ForeignKey("STOPS.uid"), primary_key=True)
    name = Column('name', String(60), primary_key = True,nullable=False)
    lang_code = Column('lang_code', String(4), nullable=False)

    stop = relationship("Stop", backref = 'name')

While I try to delete data using the code below from both the tables I get the following error,

session.query(StopName).delete()
session.query(Stop).delete()

New instance <Stop at 0xf593d50> with identity key (<class 'harmonize_station_id.core.model.Stop'>, (400000000,)) conflicts with persistent instance <Stop at 0x3bdd850>

I tried using cascade too, with following

stop = relationship("Stop", backref = 'name',cascade="delete")

I get the following error.

AttributeError: 'StopName' object has no attribute '_sa_instance_state'.

Ishan Bhatt · Accepted Answer · 2014-10-16 11:54:49Z

1

The issue was there because of the mismatch of object type of StopName. Here I was converting Stop object of client to Stop object of server(db.model). But I missed the same conversion of StopName object. So, it was trying to create StopName from client representation of it. So, i explicitly converted it to StopName of server side. It resolved the issue. So Basically, object has no attribute '_sa_instance_state' error comes when sqlalchemy interprets other kind of object as an ORM Object.

answered Oct 16, 2014 at 11:54

Ishan Bhatt

10.4k6 gold badges25 silver badges45 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Flush Error while deleting data using sqlalchemy

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related