Question

I have a table and populating it with object list then I need to use their IDs, but I am getting an

Instance <location at 0x457f3b0> is not bound to a Session; attribute refresh operation cannot proceed

error.

I am populating a list with objects and send it to a function to insert all at once. Then I try to use IDs.

Here is my insert all function:

def insertlocations(locationlist):
    session.add_all(locationlist)
    session.commit()
    session.close()

then I try to get IDs:

insertlocations(neighbourhoodlist)
session.flush(neighbourhoodlist)
for neighbourhood in neighbourhoodlist:
    print neighbourhood.locationid

Session is global by the way. Any further info needed?

The data are inserted, as I look in the MySQL table.

Answer 1

Most likely your problem is that you already close() the session in your insertlocations() function.

When you then access neighbourhood.locationid, the session is closed and thatneighbourhood object isn’t bound to a session any more.

For example, this should work:

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import sessionmaker

engine = create_engine('sqlite:///example.db')
engine.echo = True
Base = declarative_base()

class Location(Base):
    __tablename__ = 'locations'

    locationid = Column(Integer, primary_key=True)
    name = Column(String)
    address = Column(String)

    def __init__(self, name, address):
        self.name = name
        self.address = address


Base.metadata.create_all(engine)

Session = sessionmaker(bind=engine)
session = Session()

def insertlocations(locationlist):
    session.add_all(locationlist)
    session.commit()


loc1 = Location('loc1', 'Foostreet 42')
loc2 = Location('loc2', 'Barstreet 27')

neighbourhoodlist = [loc1, loc2]

insertlocations(neighbourhoodlist)
for neighbourhood in neighbourhoodlist:
    print neighbourhood.locationid

session.close()

• Move session.close() out of your function and do it after you’re done using that session.
• Ditch the session.flush(), it’s not needed since you already commit the session when you add the objects.