That was my conclusion too after consulting the googles.
I've done as you suggested and things are working as expected. Thanks!
On Monday, April 30, 2018 at 4:26:02 PM UTC-5, Mike Bayer wrote:
>
> On Mon, Apr 30, 2018 at 4:18 PM, Derek Lambert
> <dlam...@dereklambert.com <javascript:>> wrote:
> >>
> >> mmm what do you mean by "mixin" here, it looks like every class you
> >> have is mapped.
> >>
> >
> > They are mapped in the code, but that's only so I can query them. I
> > attempted to make LdapEntry and ActiveDirectoryEntry true mixin's by
> setting
> > __abstract__ = True.
> >
> >>
> >>
> >> this a heavy set of inheritance and I might also use composition
> >> instead, though that would change your DB design.
> >>
> >
> > The design isn't in production yet so now would be the time to change
> it.
> > Are you aware of any SQLAlchemy projects using composition I could
> review?
>
> mmm not specifically, it means you might do something like store
> "Entry" concepts in one table and "User" concepts in another.
> looking more closely this seems like it would be akward also.
>
> looking more closely at your mappings it looks like only
> DirectoryEntry and DirectoryUser actually have any columns. The rest
> is all synonyms. I'd likely use mixins for all those synonym sets.
>
>
> >
> > Thanks,
> > Derek
> >
> > On Monday, April 30, 2018 at 1:30:51 PM UTC-5, Mike Bayer wrote:
> >>
> >> On Mon, Apr 30, 2018 at 1:33 PM, Derek Lambert
> >> <dlam...@dereklambert.com> wrote:
> >> > I'm running into an issue in a hierarchy of single-table inheritance
> >> > objects
> >> > with multiple inheritance. The objects represent users/groups/etc.
> from
> >> > various directories and applications.
> >> >
> >> > Retrieving the list of synonyms from an object at the bottom of the
> >> > inheritance tree doesn't return the entire list of synonyms.
> >> >
> >> > When I make some of the "mixin" type objects abstract the synonyms
> >> > returned
> >> > are as expected, but I lose the ability to query those objects.
> >>
> >> mmm what do you mean by "mixin" here, it looks like every class you
> >> have is mapped.
> >>
> >> I will say that what you are doing here:
> >>
> >> class LdapUser(DirectoryUser, LdapEntry):
> >> givenName = orm.synonym('first_name')
> >> sn = orm.synonym('last_name')
> >> __mapper_args__ = {
> >> 'polymorphic_identity': 'ldap_user',
> >> }
> >>
> >> where DirectoryUser and LdapEntry are also both mapped, I'm amazed
> >> that even works. That's not at all anything that has ever been
> >> supported or attempted, as each mapper only "inherits" from at most
> >> one mapped class - while declarative supports actual "mixin" classes,
> >> where by "mixin" we mean "non-mapped class", nothing in SQLAlchemy ORM
> >> is expecting multiple inheritance at the mapper level. Above, I
> >> guess it's picking one superclass mapper at random to be "inherits",
> >> an ignoring the other, and that is likely the source of your issue.
> >> Unfortunately I think you have to work out this hierarchy in terms of
> >> single-inhertanace for classes that are actually mapped, which means
> >> adding some non-mapped "mixin" classes that just accommodate for the
> >> extra synonyms, something like:
> >>
> >> class DirectoryEntry(Base):
> >>
> >> class AbstractDirectoryUser(object):
> >> # synonyms
> >>
> >> class DirectoryUser(AbstractDirectoryUser, DirectoryEntry):
> >>
> >> class LdapEntry(DirectoryEntry):
> >>
> >> class LdapUser(AbstractDirectoryUser, LdapEntry):
> >>
> >> this a heavy set of inheritance and I might also use composition
> >> instead, though that would change your DB design.
> >>
> >>
> >> >
> >> > Maybe I'm overlooking a simpler implementation, or simply using
> >> > SQLAlchemy
> >> > in a way that wasn't intended?
> >> >
> >> > Here's a simplified subset of the code. In practice any object ending
> >> > with
> >> > Entry and the base DirectoryUser and DirectoryGroup wouldn't be
> created.
> >> >
> >> > import sqlalchemy as sa
> >> > import sqlalchemy.orm as orm
> >> > from sqlalchemy.ext.declarative import declarative_base
> >> >
> >> >
> >> > Base = declarative_base()
> >> >
> >> >
> >> > class DirectoryEntry(Base):
> >> > guid = sa.Column(sa.Integer, primary_key=True)
> >> > _type = sa.Column(sa.String, nullable=False,
> >> > index=True)
> >> > distinguished_name = sa.Column(sa.String, index=True)
> >> > name = sa.Column(sa.String, index=True)
> >> >
> >> > __tablename__ = 'directory_entry'
> >> > __mapper_args__ = {
> >> > 'polymorphic_on': _type,
> >> > 'polymorphic_identity': 'directory_entry',
> >> > }
> >> >
> >> >
> >> > class DirectoryUser(DirectoryEntry):
> >> > first_name = sa.Column(sa.String)
> >> > last_name = sa.Column(sa.String)
> >> > email = sa.Column(sa.String)
> >> > username = sa.Column(sa.String)
> >> >
> >> > __mapper_args__ = {
> >> > 'polymorphic_identity': 'directory_user',
> >> > }
> >> >
> >> >
> >> > class LdapEntry(DirectoryEntry):
> >> > cn = orm.synonym('name')
> >> >
> >> > __mapper_args__ = {
> >> > 'polymorphic_identity': 'ldap_entry',
> >> > }
> >> >
> >> >
> >> > class LdapUser(DirectoryUser, LdapEntry):
> >> > givenName = orm.synonym('first_name')
> >> > sn = orm.synonym('last_name')
> >> >
> >> > __mapper_args__ = {
> >> > 'polymorphic_identity': 'ldap_user',
> >> > }
> >> >
> >> >
> >> > class ActiveDirectoryEntry(LdapEntry):
> >> > distinguishedName = orm.synonym('distinguished_name')
> >> >
> >> > __mapper_args__ = {
> >> > 'polymorphic_identity': 'active_directory_entry',
> >> > }
> >> >
> >> >
> >> > class ActiveDirectoryUser(LdapUser, ActiveDirectoryEntry):
> >> > mail = orm.synonym('email')
> >> > sAMAccountName = orm.synonym('username')
> >> >
> >> > __mapper_args__ = {
> >> > 'polymorphic_identity': 'active_directory_user'
> >> > }
> >> >
> >> >
> >> > engine_url = 'postgresql+psycopg2://postgres@localhost/inherit_test'
> >> > engine = sa.create_engine(engine_url, echo=True)
> >> >
> >> > Base.metadata.create_all(engine)
> >> >
> >> > session = orm.sessionmaker(bind=engine)()
> >> > ad_user = ActiveDirectoryUser(
> >> > cn='John Doe',
> >> > sAMAccountName='jdoe',
> >> > distinguishedName='ou=domain',
> >> > givenName='John'
> >> > )
> >> >
> >> > session.add(ad_user)
> >> > session.commit()
> >> >
> >> > user1 = session.query(DirectoryUser).filter(DirectoryUser.username ==
> >> > 'jdoe').one()
> >> > user3 = session.query(LdapUser).filter(LdapUser.username ==
> >> > 'jdoe').one()
> >> > user2 =
> >> >
> session.query(ActiveDirectoryUser).filter(ActiveDirectoryUser.username
> >> > ==
> >> > 'jdoe').one()
> >> > user4 = session.query(DirectoryEntry).filter(DirectoryEntry.name ==
> >> > 'John
> >> > Doe').one()
> >> >
> >> > assert(user1 == user2 == user3 == user4)
> >> >
> >> > mapper = sa.inspect(ad_user.__class__)
> >> > synonyms = mapper.synonyms.keys()
> >> >
> >> > assert(synonyms == ['mail', 'sAMAccountName', 'givenName', 'sn',
> 'cn',
> >> > 'distinguishedName'])
> >> >
> >> >
> >> > Any help is appreciated!
> >> >
> >> > --
> >> > SQLAlchemy -
> >> > The Python SQL Toolkit and Object Relational Mapper
> >> >
> >> > http://www.sqlalchemy.org/
> >> >
> >> > To post example code, please provide an MCVE: Minimal, Complete, and
> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a
> full
> >> > description.
> >> > ---
> >> > 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+...@googlegroups.com.
> >> > To post to this group, send email to sqlal...@googlegroups.com.
> >> > Visit this group at https://groups.google.com/group/sqlalchemy.
> >> > For more options, visit https://groups.google.com/d/optout.
> >
> > --
> > SQLAlchemy -
> > The Python SQL Toolkit and Object Relational Mapper
> >
> > http://www.sqlalchemy.org/
> >
> > To post example code, please provide an MCVE: Minimal, Complete, and
> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> > description.
> > ---
> > 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+...@googlegroups.com <javascript:>.
> > To post to this group, send email to sqlal...@googlegroups.com
> <javascript:>.
> > Visit this group at https://groups.google.com/group/sqlalchemy.
> > For more options, visit https://groups.google.com/d/optout.
>
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
---
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.
