Hi everyone!
I'm puzzled by a behaviour shown by SA 0.6.5 that 0.5.8 didn't show,
and I'm wondering what I'm doing wrong.. I have a simple uncascaded
many-to-many relationship, and if I try the following:
1) save a child
2) close the session
3) associate the child to a parent and save the parent
4) deassociate the child and save the parent
the association doesn't get removed from the junction table.. If I
skip closing the session, it DOES get removed...
Here's an example:
from sqlalchemy import Column, String, Integer, Table, ForeignKey
from sqlalchemy.engine import create_engine
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
junction = Table("junction", Base.metadata, Column("p_id",
ForeignKey("parents.id")),
Column("c_id",
ForeignKey("children.id")))
class Child(Base):
__tablename__ = "children"
id = Column(Integer, primary_key=True)
class Parent(Base):
__tablename__ = "parents"
id = Column(Integer, primary_key=True)
children = relationship(Child, secondary=junction, cascade="")
def save(session, x):
session.add(x)
session.flush()
en = create_engine("sqlite:///:memory:", echo=True)
Base.metadata.create_all(en)
maker = sessionmaker(en)
session = maker(autocommit=True)
# Save a child and close the session
c = Child()
save(session, c)
session.close()
# Associate the child to a parent and save
p = Parent()
p.children = [c]
save(session, p)
# Try to remove the child
p.children = []
save(session, p)
I'd expect that the last command would log something like
BEGIN (implicit)
SELECT children.id AS children_id
FROM children
WHERE children.id = ?
(1,)
DELETE FROM junction WHERE junction.p_id = ? AND junction.c_id = ?
(1, 1)
COMMIT
SELECT parents.id AS parents_id
FROM parents
WHERE parents.id = ?
(1,)
but instead I get only
BEGIN (implicit)
COMMIT
SELECT parents.id AS parents_id
FROM parents
WHERE parents.id = ?
(1,)
This used to work with 0.5.8, what am I doing wrong?
Many thanks for your attention!
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