Hi,
Newbie question on relationships.
Consider the following code.
When deleting a child, I would like the parent *.children* attribute to be
automatically updated by the orm.
It is not : am I doing something wrong or missed some configuration ?
Thanks a lot!
Pierre
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import os
import sqlite3
from sqlalchemy import *
from sqlalchemy.types import *
from sqlalchemy.orm import *
from sqlalchemy.pool import NullPool
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
METADATA = Base.metadata
DB_NAME = "example.db"
class Child(Base):
__tablename__ = 'children'
id = Column(Integer, primary_key=True)
name = Column(String(20), nullable=False)
# Many to One Child --- Parent
timeslot_id = Column(Integer, ForeignKey('parent.id'))
timeslot = relationship("Parent", backref="children")
def __init__(self, name):
self.name = name
def __repr__(self):
return self.name
class Parent(Base):
__tablename__ = 'parent'
id = Column(Integer, primary_key=True)
name = Column(String(20), nullable=False)
def __init__(self, name):
self.name = name
def __repr__(self):
return self.name
if os.path.exists(DB_NAME):
os.remove(DB_NAME)
engine = create_engine('sqlite:///%s' % DB_NAME,
connect_args={'detect_types':
sqlite3.PARSE_DECLTYPES|
sqlite3.PARSE_COLNAMES},
poolclass=NullPool,
)
def print_family(parent):
print "%s's family:" % parent
for child in parent.children:
print "|____ %s" % child
session_maker = sessionmaker()
METADATA.create_all(engine)
session_maker.configure(bind=engine, expire_on_commit=False)
session = session_maker()
peter = Parent(name="Peter")
dan = Child(name="Dan")
jenny = Child(name="Jenny")
peter.children.append(dan)
peter.children.append(jenny)
session.add_all([dan, jenny, peter])
session.commit()
children = session.query(Child).all()
print children
parents = session.query(Parent).all()
for parent in parents:
print_family(parent)
session.delete(dan)
session.commit()
print "Deleted Dan !"
for parent in parents:
print_family(parent)
print "??? Dan is still in Peter's family..."
children = session.query(Child).all()
print children
print "... but not in the children list... :-("
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