Hi all,
I have a simple m2m relationship between two entities, with a secondary table
in the middle.
>From the left item I need to read both the right items and the middle ones, so
I have two relationships on the left entity.
When I delete one left item, I get the following exception:
AssertionError: Dependency rule tried to blank-out primary key column
'persons2activities.idperson' on instance
'<PersonActivity...>
I tried to investigate, but without luck. Am I missing something?
The following script exhibits the problem:
from sqlalchemy import create_engine
from sqlalchemy import Column, Integer, ForeignKey, String
from sqlalchemy.orm import relationship, sessionmaker
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class Person(Base):
__tablename__ = 'persons'
id = Column(Integer, primary_key=True, nullable=False)
name = Column(String, nullable=False)
activities = relationship('Activity', secondary='persons2activities')
class Activity(Base):
__tablename__ = 'activities'
id = Column(Integer, primary_key=True, nullable=False)
name = Column(String, nullable=False)
class PersonActivity(Base):
__tablename__ = 'persons2activities'
idperson = Column(Integer, ForeignKey('persons.id'), nullable=False,
primary_key=True)
idactivity = Column(Integer, ForeignKey('activities.id'), nullable=False,
primary_key=True)
# Comment out the following, and everything works without errors
person = relationship(Person, backref='preferred_activities')
def main():
engine = create_engine('sqlite:///:memory:', echo=True)
Session = sessionmaker(bind=engine)
sess = Session()
Base.metadata.create_all(engine)
person = Person(id=1, name='lele')
activity = Activity(id=1, name='carrom')
person.activities.append(activity)
sess.add(person)
sess.flush()
sess.commit()
sess.expunge_all()
person = sess.query(Person).get(1)
sess.delete(person)
sess.flush()
sess.commit()
if __name__ == '__main__':
main()
Thanks in advance,
ciao, lele.
--
nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri
real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia.
l...@metapensiero.it | -- Fortunato Depero, 1929.
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sqlalchemy+unsubscr...@googlegroups.com.
To post to this group, send email to sqlalchemy@googlegroups.com.
Visit this group at https://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.
