On Apr 28, 2008, at 12:07 PM, Gaetan de Menten wrote:
> pjoin = polymorphic_union({
> 'manager':managers_table,
> 'engineer':engineers_table,
> 'hacker':hackers_table
> }, 'type', 'pjoin')
>
> mapper(Company, companies, properties={
> 'engineers':relation(Engineer, lazy=False,
> enable_typechecks=False)
> })
> employee_mapper = mapper(Employee, pjoin,
> polymorphic_on=pjoin.c.type)
> manager_mapper = mapper(Manager, managers_table,
> inherits=employee_mapper, concrete=True,
> polymorphic_identity='manager')
> engineer_mapper = mapper(Engineer, engineers_table,
> inherits=employee_mapper, concrete=True,
> polymorphic_identity='engineer',
> properties={'company': relation(Company)})
> hacker_mapper = mapper(Hacker, hackers_table,
> inherits=engineer_mapper,
> concrete=True,
> polymorphic_identity='hacker',
> properties={'company': relation(Company)})
OK...mapping Employee to pjoin is fine since its a "virtual" mapper.
For engineer_mapper, it needs a selectable from which it can also load
Hacker objects...this is the "pjoin2" polymorphic_union you've created
in a later test. *but*, the engineer_mapper doesn't get mapped to it,
it should use it as its "with_polymorphic" argument (which used to be
handled by "select_table"):
pjoin = polymorphic_union(...)
pjoin2 = polymorphic_union(...)
employee_mapper = mapper(Employee, pjoin, polymorphic_on=pjoin.c.type)
manager_mapper = mapper(Manager, managers_table,
inherits=employee_mapper, concrete=True, polymorphic_identity='manager')
engineer_mapper = mapper(Engineer, engineers_table,
with_polymorphic=('*', pjoin2),
polymorphic_on=pjoin2.c.type,
inherits=employee_mapper, concrete=True,
polymorphic_identity='engineer')
hacker_mapper = mapper(Hacker, hackers_table, inherits=engineer_mapper,
concrete=True, polymorphic_identity='hacker')
this should in theory also fix the "engineers" relation on Company.
But as I've said many times (to svil, at least) concrete inheritance
is something i havent gotten into much as of yet, largely due to the
many inherent issues with it as well as its being a generally
unpopular pattern, so there may still be issues with this setup (but
let me know, since thats how it "should" work).
In any case the unit tests which you were working from (im guessing
test/orm/inheritance/concrete.py) should be patched to include this
test (i.e. including Hacker, the polymorphic load, as well as the
relation). Assuming it works we should also make sure the 0.5 branch
(which isnt called that yet) can handle it too.
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