I'm on version 0.5.3, I will try it on 0.5.6 tomorrow.
The check for column present above could be the problem... The column
that I'm adding in the select is a func.coalesce(...).label
('something') and the my_super_table select that I'm mapping to is
aliased... Would that throw off the "column in table" check?
Thanks for the speedy reply!
Ben
On 14 Dec, 17:45, "Michael Bayer" <[email protected]> wrote:
> boothead wrote:
> > Hi,
>
> > I have a parent/superclass object in a polymorphic relationship which
> > is mapped against a select. The select is a table and a coalesce
> > function (the coalesce is to make up for the fact that the
> > polymorphic_on column doesn't exist).
>
> > All seems to be working fine on update, create etc but delete is
> > coming a cropper here:
>
> > /sqlalchemy/orm/mapper.pyc in _delete_obj(self, states,
> > uowtransaction)
> > 1459 mapper = table_to_mapper[table]
> > 1460 clause = sql.and_()
> > -> 1461 for col in mapper._pks_by_table[table]:
> > 1462 clause.clauses.append(col == sql.bindparam
> > (col.key, type_=col.type))
> > 1463 if mapper.version_id_col and
> > table.c.contains_column(mapper.version_id_col):
>
> > KeyError: Table('map_table', MetaData
> > (<sqlalchemy.engine.base.Connection object at 0x8751210>), Column
> > (...), ....)
>
> what version sqla you're on ? The line numbers aren't ordered that way
> in 0.5.6. The dict lookup there should not be reachable as there's a
> check for column present in the pks dict up above that would prevent the
> delete collection from being populated. That code definitely needs a
> little adjustment as its looping unnecessarily but still should be working
> the way it is.
>
>
>
> > In this instance map_table (names changed to protect the guilty) is
> > our child table and I've just done:
>
> > In [32]: q = ses.query(ChildClass)
>
> > In [33]: h = q[0]
>
> > In [34]: ses.delete(h)
>
> > In [35]: ses.flush()
>
> > At which point "kaboom".
>
> > Interestingly the 'mapper' in question in the traceback is the mapper
> > for a different child class i.e. NOT ChildClass in the ipython
> > example above, but 'table' is the the table mapped to ChildClass.
>
> > There are three of these child tables, all configured the same way and
> > one of them actually works for deleting. The one type of child class
> > that I can delete also belongs mapper in question when I get the above
> > traceback when trying to delete instances of the other two children. I
> > don't know if that's significant or not?
>
> > The only columns in the map_table are a foreign key to the parent
> > table / superclass and a foreign key to a related object (which are a
> > composite primary key) and an additional column.
>
> > I'm pretty sure that I'm doing something nasty, but the only really
> > out of the ordinary thing (as compared with the documentation) is that
> > the super class is mapped to something like:
>
> > my_super_table = select([superclass_table, func.coalesce
> > (<some_stuff>)]).alias('my_superclass_table')
>
> > This is the gist of the SQL that
>
> >>>> print select(my_super_table)
>
> > gives:
>
> > SELECT my_super_table.col1 ...
> > FROM
> > (SELECT h.col1 ...,
> > coalesce(
> > (SELECT 'C' FROM child1_map
> > WHERE child1_map.holiday_id = h.holiday_id),
> > (SELECT 'E' FROM dots.child2_map
> > WHERE child2_map.holiday_id = h.holiday_id),
> > (SELECT 'I' FROM child3_map
> > WHERE child1_map.holiday_id = h.holiday_id)
> > ) AS my_polymorphic_column
> > FROM the_old_table h) my_super_table
>
> > This is the sql I want, and as I mentioned update and select seems to
> > be fine
>
> > So, is this a problem with incorrectly configuring cascade rules, or
> > have I found a corner case that should work but doesn't..?
>
> > Cheers,
> > Ben
>
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