[Sqlalchemy-tickets] Issue #4131: Object deleted by delete-orphan not marked as deleted (zzzeek/sqlalchemy)

[erdnaxeli <iss...@bi...>]

New issue 4131: Object deleted by delete-orphan not marked as deleted
https://bitbucket.org/zzzeek/sqlalchemy/issues/4131/object-deleted-by-delete-orphan-not-marked

erdnaxeli:

Hi,

When removing an object from a collection, if this object is deleted because of `cascade="all, delete-orphan'`, the object is not marked as deleted.

```
#!/usr/bin/env python

from sqlalchemy import Column, ForeignKey, Integer, String, create_engine, event
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.inspection import inspect
from sqlalchemy.orm import backref, relationship, sessionmaker

engine = create_engine('sqlite:///:memory:', echo=True)
Base = declarative_base()

class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String)


class Pet(Base):
    __tablename__ = 'pets'

    id = Column(Integer, primary_key=True)
    user_id = Column(Integer, ForeignKey('users.id'), nullable=False)
    name = Column(String)

    user = relationship(
        'User',
        backref=backref('pets', cascade='all, delete-orphan')
    )


Base.metadata.create_all(engine)

Session = sessionmaker(bind=engine)
session = Session()


@event.listens_for(Session, 'after_flush')
def do_something_with_updated_objects(session, flush_context):
    for obj in session.dirty:
        print(obj.name)
        i = inspect(obj)
        if not i.deleted:
            session.refresh(obj)


print('> Create objects')
george = User(id=1, name='George')
rex = Pet(id=1, name='Rex')
george.pets.append(rex)

session.add(george)
session.commit()

print('> Remove Rex')
george = session.query(User).filter_by(name='George').scalar()
assert(len(george.pets) == 1)

rex = george.pets[0]
# removing Rex will actually delete it, because of delete-orphan
george.pets.remove(rex)
session.add(george)
session.commit()

george = session.query(User).filter_by(name='George').scalar()
assert(len(george.pets) == 0)
```

Output:
```
> Create objects
2017-11-07 19:03:07,351 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2017-11-07 19:03:07,352 INFO sqlalchemy.engine.base.Engine INSERT INTO users (id, name) VALUES (?, ?)
2017-11-07 19:03:07,352 INFO sqlalchemy.engine.base.Engine (1, 'George')
2017-11-07 19:03:07,352 INFO sqlalchemy.engine.base.Engine INSERT INTO pets (id, user_id, name) VALUES (?, ?, ?)
2017-11-07 19:03:07,353 INFO sqlalchemy.engine.base.Engine (1, 1, 'Rex')
2017-11-07 19:03:07,353 INFO sqlalchemy.engine.base.Engine COMMIT
> Remove Rex
2017-11-07 19:03:07,353 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2017-11-07 19:03:07,354 INFO sqlalchemy.engine.base.Engine SELECT users.id AS users_id, users.name AS users_name 
FROM users 
WHERE users.name = ?
2017-11-07 19:03:07,354 INFO sqlalchemy.engine.base.Engine ('George',)
2017-11-07 19:03:07,354 INFO sqlalchemy.engine.base.Engine SELECT pets.id AS pets_id, pets.user_id AS pets_user_id, pets.name AS pets_name 
FROM pets 
WHERE ? = pets.user_id
2017-11-07 19:03:07,354 INFO sqlalchemy.engine.base.Engine (1,)
2017-11-07 19:03:07,355 INFO sqlalchemy.engine.base.Engine DELETE FROM pets WHERE pets.id = ?
2017-11-07 19:03:07,355 INFO sqlalchemy.engine.base.Engine (1,)
Rex
2017-11-07 19:03:07,356 INFO sqlalchemy.engine.base.Engine SELECT pets.id AS pets_id, pets.user_id AS pets_user_id, pets.name AS pets_name 
FROM pets 
WHERE pets.id = ?
2017-11-07 19:03:07,356 INFO sqlalchemy.engine.base.Engine (1,)
2017-11-07 19:03:07,356 INFO sqlalchemy.engine.base.Engine ROLLBACK
Traceback (most recent call last):
  File "t.py", line 61, in <module>
    session.commit()
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 921, in commit
    self.transaction.commit()
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 461, in commit
    self._prepare_impl()
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 441, in _prepare_impl
    self.session.flush()
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2192, in flush
    self._flush(objects)
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2312, in _flush
    transaction.rollback(_capture_exception=True)
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/util/langhelpers.py", line 66, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2280, in _flush
    self.dispatch.after_flush(self, flush_context)
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/event/attr.py", line 218, in __call__
    fn(*args, **kw)
  File "t.py", line 43, in do_something_with_updated_objects
    session.refresh(obj)
  File "/home/amorigno/bacasable/delete/.venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 1474, in refresh
    instance_str(instance))
sqlalchemy.exc.InvalidRequestError: Could not refresh instance '<Pet at 0x7f21393a5490>'
```

I would expect `i.deleted` to be `True`.

SQLAlchemy==1.1.15
Python 2.7.6