Attached is a script that attempts to imitate as close as I can tell
to what you are asking (and the end result is correct). Modify it to
illustrate your exact issue.
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from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.orm.session import Session
from sqlalchemy.ext.declarative import declarative_base
engine = create_engine('sqlite://', echo=True)
Base = declarative_base()
class Parent(Base):
__tablename__ = 'parent'
id = Column(Integer, primary_key=True)
data = Column(String)
children = relation("Child", lazy=False)
class Child(Base):
__tablename__ = 'child'
id = Column(Integer, primary_key=True)
data = Column(String)
parent_id = Column(Integer, ForeignKey('parent.id'))
Base.metadata.create_all(engine)
engine.execute(Parent.__table__.insert(), {'id':1, 'data':'parent1'})
engine.execute(Child.__table__.insert(), {'id':1, 'data':'child1', 'parent_id':1})
engine.execute(Child.__table__.insert(), {'id':2, 'data':'child2', 'parent_id':1})
session = Session(bind=engine, autoflush=False,
_enable_transaction_accounting=False, autocommit=True,
weak_identity_map=True)
parent = session.query(Parent).first()
children = session.query(Child).all()
assert parent.children == children
query = session.query(Parent)
query = query.with_lockmode('update')
query = query.options(lazyload(Parent.children))
query = query.filter_by(id=parent.id)
query = query.populate_existing()
rows = query.all()
parent = rows[0]
assert parent.children == children
On Sep 27, 2008, at 1:52 PM, Mike Bernson wrote:
>
> I have a problem with row coming back form mapped class that has
> relations.
>
> The session is created with:
>
> self.session = Session(bind=self._engine, autoflush=False,
> _enable_transaction_accounting=False, autocommit=True,
> weak_identity_map=True)
>
>
> The problem occurs with instance on that have already been loaded
> and the query
> ask for lazyload of some of the relations. The first query load a
> bunch of row. The
> second query does the follow:
>
> query = session.query(mapped_class)
> query = query.with_lockmode('update')
> query = query.options(lazyload(relation1)
> query = query.options(lazyload(relation2)
> query = query.filter_by(id=234)
> query = query.populate_existing()
>
> rows = query.all()
>
> In the rows relation1 and relation2 both are not none. All the data
> in relation1 and relation2 is
> None. If I remove the lazyload and try it I get data in relation1
> and relation2.
>
> What I am trying to do is update the instance to match the data and
> create locks for
> all but the tables that are lazyload.
>
> There are no other references to relation1 and relation2.
>
> I have not verified but It look like if a relation has other
> references the relation has data in it
> columns.
> This happens in both 0.5b3 and 0.5rc1.
>
>
>
>
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>
