Hi everyone, I'm writing a script using sqlalchemy 0.66 and sqlite3.
In my script I'm trying to set up a one to one relation between two
tables via ORM. Here is a simplified code showing my situation:
from sqlalchemy import *
from sqlalchemy.orm import *
class Parent(object) :
def __init__(self, name) :
self.name = name
class Child(object) :
def __init__(self, name) :
self.name = name
engine = create_engine("sqlite:///test.db", echo=False)
metadata = MetaData(engine)
prn_tab = Table("parent", metadata,
Column('id', Integer, primary_key=True),
Column('name', String),
sqlite_autoincrement=True)
prn_tab.create()
chl_tab = Table("child", metadata,
Column('id', Integer, primary_key=True),
Column('name', String),
sqlite_autoincrement=True)
chl_tab.create()
fck = ForeignKeyConstraint
chl_tab.append_constraint(fck([chl_tab.c.id], [prn_tab.c.id]))
rel = relationship(Child, uselist=False, passive_deletes=True)
mapper(Parent, prn_tab, properties={"child":rel})
mapper(Child, chl_tab)
Session = sessionmaker()
Session.configure(bind=engine)
session = Session()
session.add(Child("Carl"))
session.commit()
if you run the above code you will see that the commit statement
generates the following error:
sqlalchemy.orm.exc.FlushError: Instance <Child at 0x1087b30> has a
NULL identity key. Check if this flush is occuring at an
inappropriate time, such as during a load operation.
I really cannot understand the reason why this error is raised....can
anyone give a hint? Tahnks in advance!
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