On Fri, Oct 19, 2018 at 2:30 PM Derek Lambert <dlamb...@dereklambert.com> wrote:
>
> I'm replying to my original post since it's related.
>
> I'm still seeing missing synonyms on child classes when they are defined in a
> mixin imported on a parent.
>
>
> import sqlalchemy as sa
> from sqlalchemy import orm
> from sqlalchemy.ext.declarative import declarative_base, declared_attr
>
>
> Base = declarative_base()
>
>
> class DirectoryEntry(Base):
> guid = sa.Column(sa.Integer, primary_key=True)
> _type = sa.Column(sa.String, nullable=False)
> distinguished_name = sa.Column(sa.String)
> name = sa.Column(sa.String)
>
> __tablename__ = 'directory_entry'
> __mapper_args__ = {
> 'polymorphic_on': _type,
> 'polymorphic_identity': 'directory_entry',
> }
>
>
> class DirectoryGroup(DirectoryEntry):
> __mapper_args__ = {
> 'polymorphic_identity': 'directory_group',
> }
>
>
> class ActiveDirectoryEntry:
> @declared_attr
> def distinguishedName(self):
> return orm.synonym('distinguished_name')
>
>
> class ActiveDirectoryGroup(ActiveDirectoryEntry, DirectoryGroup):
> __mapper_args__ = {
> 'polymorphic_identity': 'active_directory_group'
> }
>
>
> class AnotherChild(ActiveDirectoryGroup):
> __mapper_args__ = {
> 'polymorphic_identity': 'another_child'
> }
>
>
> engine =
> sa.create_engine('postgresql+psycopg2://postgres@localhost/postgres',
> echo=True, isolation_level='AUTOCOMMIT')
>
> engine.execute('DROP DATABASE IF EXISTS inherit_test')
> engine.execute('CREATE DATABASE inherit_test')
>
> engine =
> sa.create_engine('postgresql+psycopg2://postgres@localhost/inherit_test',
> echo=True)
>
> Base.metadata.create_all(engine)
>
> session = orm.sessionmaker(bind=engine)()
> group = ActiveDirectoryGroup(
> name='Users',
> distinguishedName='cn=Users,ou=domain',
> )
> child = AnotherChild(
> name='Admins',
> distinguishedName='cn=Admins,ou=domain',
> )
>
> session.add(group)
> session.add(child)
> session.flush()
> session.commit()
>
> group =
> session.query(ActiveDirectoryGroup).filter(ActiveDirectoryGroup.name ==
> 'Users').one()
> group_mapper = sa.inspect(group.__class__)
> group_synonyms = group_mapper.synonyms.keys()
>
> child = session.query(AnotherChild).filter(AnotherChild.name ==
> 'Admins').one()
> child_mapper = sa.inspect(child.__class__)
> child_synonyms = child_mapper.synonyms.keys()
>
> assert child_synonyms == group_synonyms
>
>
> Maybe I'm off in unsupported land again? I could define AnotherChild
> identical to ActiveDirectoryGroup, but there are additional synonyms on
> ActiveDirectoryGroup they both should have.
the synonym() is only applied to ActiveDirectoryGroup because it is
naturally inherited by AnotherChild:
child_synonyms = child_mapper.inherits.synonyms.keys()
assert child_synonyms == group_synonyms
but it's not getting mapped anyway, which seems like a bug. works
with @cascading though:
class ActiveDirectoryEntry:
@declared_attr.cascading
def distinguishedName(cls):
return orm.synonym('distinguished_name')
c1 = session.query(AnotherChild.distinguishedName).filter(
AnotherChild.distinguishedName == "cn=Admins,ou=domain").scalar()
g1 = session.query(ActiveDirectoryGroup.distinguishedName).filter(
ActiveDirectoryGroup.distinguishedName == "cn=Users,ou=domain").scalar()
print(g1)
print(c1)
>
> Thanks,
> Derek
>
> On Wednesday, May 9, 2018 at 2:16:22 PM UTC-5, Derek Lambert wrote:
>>
>> 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> 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.
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>>> >
>>> > --
>>> > SQLAlchemy -
>>> > The Python SQL Toolkit and Object Relational Mapper
>>> >
>>> > http://www.sqlalchemy.org/
>>> >
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>
> --
> 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.
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--
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http://www.sqlalchemy.org/
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