the Document class starts out as unmapped. then when you call prepare() (or
whatever it's called for ACB), it calls the polymorphic_union() function and
them maps Document to that. This union has just columns in it, e.g. _name in
this case. There's no attempt to reconcile column labels used on descendant
classes to the superclass. You could have another class ActualDocument2 that
has a column "name_" but a different attribute name.
On Sep 5, 2014, at 7:53 PM, Alex Grönholm <alex.gronh...@nextday.fi> wrote:
> Sorry to be asking more questions, but the docs on inheritance don't get into
> much details on how the properties are supposed to work.
> The following code produces unexpected results:
>
> from sqlalchemy import *
> from sqlalchemy.orm import *
> from sqlalchemy.ext.declarative import AbstractConcreteBase, declarative_base
>
> Base = declarative_base()
>
>
> class Document(Base, AbstractConcreteBase):
> doctype = Column('doc_type', Unicode, nullable=False)
>
>
> class ActualDocument(Document):
> __tablename__ = 'actual_documents'
> __mapper_args__ = {'concrete': True, 'polymorphic_identity': 'actual'}
>
> id = Column(Integer, primary_key=True)
> name = Column('name_', Unicode)
>
> configure_mappers()
>
> for prop in class_mapper(Document).column_attrs:
> print('%s (%s)' % (prop, prop.__class__.__name__))
>
> for prop in class_mapper(ActualDocument).column_attrs:
> print('%s (%s)' % (prop, prop.__class__.__name__))
>
> Which gives me:
>
> Document.doc_type (ColumnProperty)
> Document.id (ColumnProperty)
> Document.name_ (ColumnProperty)
> Document.type (ColumnProperty)
> ActualDocument.doctype (ColumnProperty)
> ActualDocument.name (ColumnProperty)
> ActualDocument.id (ColumnProperty)
>
> I can understand Document.id (which comes from ActualDocument) and
> Document.type (which I assume is the polymorphic identity) but doc_type seems
> wrong to me. Why are doc_type and name_ not named doctype and name
> respectively, like they are on ActualDocument? Is this a bug? Am I right in
> guessing that the polymorphic union simply lacks the proper labels where the
> column name differs from the attribute name?
>
>
> --
> 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 http://groups.google.com/group/sqlalchemy.
> For more options, visit https://groups.google.com/d/optout.
--
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 http://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.
