you need to set "cascade='all, delete-orphan' on the relation
referencing the AssociationProxy. Some docs on ORM cascades are in
the ORM tutorial as well as
http://www.sqlalchemy.org/docs/04/session.html#unitofwork_cascades
.
On May 21, 2008, at 12:14 PM, kremlan wrote:
>
> I've posted the following question on the Elixir group and they sent
> me here.
>
> My setup
>
> ##
> # Tables
> ##
> roles = Table('roles', meta,
> Column('id', Integer, primary_key=True),
> Column('name', String(25))
> )
>
> users = Table('users', meta,
> Column('id', Integer, primary_key=True),
> Column('username', String(125)),
> Column('password', String(125)),
> ....
> )
>
> users_roles = Table('users_roles', meta,
> Column('user_id', Integer, primary_key=True),
> Column('role_id', Integer, primary_key=True),
> ....
> ForeignKeyConstraint(['user_id'], ['users.id']),
> ForeignKeyConstraint(['role_id'], ['roles.id'])
> )
>
> ##
> # Elixir models
> ##
>
> class UserRole(Entity):
> using_options(tablename='users_roles', autoload=True)
> user = ManyToOne('User', colname='user_id')
> role = ManyToOne('Role', colname='role_id')
>
> class Role(Entity):
> using_options(tablename='roles', autoload=True)
> users_roles = OneToMany('UserRole')
> users = AssociationProxy('users_roles', 'user')
>
> class User(Entity):
> using_options(tablename='users', autoload=True)
> users_roles = OneToMany('UserRole')
> roles = AssociationProxy('users_roles', 'role')
>
> This setup works fine for reading but not for updating or deleting.
>
> I was able to then get the append method working via the following
>
> def _create_ur_by_role(role):
> return UserRole(role=role)
>
> in class User:
> roles = AssociationProxy('users_roles', 'role',
> creator=_create_ur_by_role)
>
> I am still unable to delete roles. Example:
> me.roles.pop() < -- works fine
> session.flush()
>
> results in...
>
> AssertionError: Dependency rule tried to blank-out primary key column
> 'users_roles.user_id'
>
> I have tried adding ondelete='cascade' to the UserRole model. This
> caused no change.
>
> Any help will be greatly appreciated
>
> -brad
>
> >
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