this issue is not specific to the recent changes; this would happen
even with the old behavior (since exclude_properties was meant to
mean, "I dont want SQLA to know about this column at all" typically in
a reflection scenario). its fixed in r4966.
On Jul 22, 2008, at 7:27 AM, Malthe Borch wrote:
>
> Michael Bayer wrote:
>> well, i can support this in 0.5 trunk. in rev 4965, If a descriptor
>> is present on a class, or if the name is excluded via the include/
>> exclude lists, the attribute will not be instrumented via the
>> inherited mapper or via the mapped Table. So your example works with
>> just the @property alone.
>
> I've managed to demonstrate the issue in an isolated test (see below).
> The only change from the previous is that I've set a default value.
>
> This causes SQLAlchemy to *prefetch* the 'col' column, but this throws
> an exception since the column is not mapped.
>
> from sqlalchemy import *
> from sqlalchemy.orm import *
>
> e = create_engine('sqlite://')
> m = MetaData(e)
>
> t1= Table(
> 't1', m,
> Column('id', Integer, primary_key=True),
> Column('col', String(50), default=u""),
> )
> t1.create()
>
> t2= Table(
> 't2', m,
> Column('id', Integer, ForeignKey("t1.id"), primary_key=True),
> Column('data', String(50)),
> )
> t2.create()
>
> class T1(object):
> pass
>
> class T2(T1):
> @property
> def col(self):
> return u"Some read-only value."
>
> polymorphic = (
> [T2], t1.join(t2))
>
> mapper(T1, t1)
> mapper(
> T2, t2,
> exclude_properties=('col',),
> with_polymorphic=polymorphic,
> inherits=T1,
> inherit_condition=(t1.c.id==t2.c.id),
> )
>
> sess = sessionmaker()()
> x = T2()
>
> assert type(T2.col) is property
>
> x.data = "some data"
> sess.save(x)
> sess.commit()
> sess.clear()
>
> assert sess.query(T2).one().data == "some data"
> assert sess.query(T2).one().col == u"Some read-only value."
>
> x = sess.query(T2).one()
> x.data = "some new data"
> sess.commit()
> assert sess.query(T2).one().data == "some new data"
>
>
> >
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