On Jan 30, 2010, at 9:07 AM, avdd wrote:
> I'm using session.add() to refresh my objects while working on them,
> because I don't want to merge them with the persistent state. But it
> appears deletes aren't carrying across to child relations:
in r6711 the save-update cascade operation will cascade related objects present
in the full history of a scalar- or collection- holding relation() attribute
into the new session, thus allowing objects marked as deleted or disassociated
from the parent to be present in the new session where they will particpate in
the next flush().
>
>
> $ cat listdelete.py; python listdelete.py
>
> import sqlalchemy as sql
> from sqlalchemy import orm
> from sqlalchemy.ext.declarative import declarative_base
>
> echo = 0
> engine = sql.create_engine("sqlite:///:memory:", echo=bool(echo))
> metadata = sql.MetaData(bind=engine)
> DB = orm.sessionmaker(bind=engine)
> T = declarative_base(metadata=metadata)
>
> class A(T):
> __tablename__ = 'a'
> id = sql.Column(sql.Integer, primary_key=True)
> info = sql.Column(sql.String)
> cc = orm.relation('C',
> backref='a',
> cascade='all,delete-orphan')
> def __repr__(self):
> return " >> a: %s cc=%s" % (self.info, len(self.cc))
>
> class C(T):
> __tablename__ = 'c'
> a_id = sql.Column(sql.Integer, sql.ForeignKey('a.id'),
> primary_key=True)
> i = sql.Column(sql.Integer, primary_key=True)
>
> def get():
> return DB().query(A).first()
>
> def change(a, s, i):
> orm.object_session(a).close()
> db = DB()
> db.add(a)
> a.info = s
> del a.cc[-1]
> a.cc.append(C(i=i))
> db.close()
>
> metadata.create_all()
> A.__table__.delete().execute()
>
> db = DB()
> a = A(id=1, info='blah', cc=[C(i=1), C(i=2)])
> db.add(a)
> db.commit()
> db.close()
>
> print get()
>
> # merge and flush
> a = get()
> change(a, 'change one', 3)
> db = DB()
> db.merge(a)
> db.commit()
> db.close()
>
> print get()
>
> # add and flush
> a = get()
> change(a, 'change two', 4)
> db = DB()
> db.add(a)
> db.commit()
> db.close()
>
> print get()
>
>
>>> a: blah cc=2
>>> a: change one cc=2
>>> a: change two cc=3
>
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