So I am new to SQLAlchemy, and I would like after a new User object is created that a Permissions object is created by default. Reading the documentation it seems that after_insert mapper event is what I should be using. The problem is that the event listener is called before the object is actually committed.
Is there a way to have the Permissions object at least put in possibly a transaction or on the list of objects to be created after the user object is actually committed.
class Users():
__tablename__ = 'users'
user_id = Column(String(36), primary_key=True, nullable=False)
class Permissions():
__tablename__ = 'permissions'
user_id = Column(String(36), ForeignKey('users.user_id'), primary_key=True,
nullable=False)
@event.listens_for(Users, "after_insert")
def create_permissions(mapper, connection, user):
connection.execute(Permissions.__table__.insert(user_id=user.user_id))
IntegrityError: (IntegrityError) (1452, 'Cannot add or update a child row: a foreign key constraint fails
Ideally I would like to do this without a Database Trigger on the Users table.
So by changing my class defintions around, and attaching the session object to each class I am able to add a new Permissions object at time after_insert is signaled. And the proper sequences of commits take place.
class Users():
__tablename__ = 'users'
user_id = Column(String(36), primary_key=True, nullable=False)
............
class Permissions():
__tablename__ = 'permissions'
user_id = Column(String(36), ForeignKey('users.user_id'), primary_key=True,
nullable=False)
............
@event.listens_for(Users, "after_insert")
def create_permissions(mapper, connection, user):
user.session.add(Permissions(user_id=user.user_id))