This solution didn't work for me, because "polymorphic_on" column was
actually a ForeignKey.
So when value was null, it worked, but in other cases it didnt.
But I've managed to find a solution..
# Version
parent_id = # UUID
parent = ... # Version
parent_exists = case([(parent_id != None, "revision")], else_="original")
__mapper_args__ = {'polymorphic_on': parent_exists}
# Revision(Version)
__mapper_args__ = {'polymorphic_identity': 'revision'}
# Original(Version)
__mapper_args__ = {'polymorphic_identity': 'original'}
On Friday, May 3, 2013 6:27:14 PM UTC+2, Michael Bayer wrote:
>
>
> On May 3, 2013, at 12:20 PM, Goran Popovic <[email protected]<javascript:>>
> wrote:
>
> > Table Versions
> >
> > # ID
> > # PARENT_ID
> > # TEXT
> >
> > If parent_id == Null:
> > its ORIGINAL
> >
> > if parent_id != Null:
> > it's REVISION
> >
> > Is it possible to achieve this with polymorphic_identity?
> >
> > It seems that polymorphic_identity doesn't support NULL and not NULL
> >
> > __mapper_args__ = {
> > 'polymorphic_identity':'original'
> > }
>
> not built in, but see the recipe at
> http://www.sqlalchemy.org/trac/ticket/1409#comment:3 .
>
>
>
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