On Jun 7, 7:05 pm, svilen <[EMAIL PROTECTED]> wrote:
> what is your hierarchy?
> why Boss' mapper inherits from person's one, and not from manager's
> one?
Yes it was a mistake indeed.
Going further with other tests i still notice something that can't be
easily done. Summarizing the setup, classes are::
class Employee(object): pass
class Manager(Employee): pass
class Boss(Manager): pass
while the mapper is::
person_join = polymorphic_union(
{
'person':employees.select(employees.c.type=='person'),
'engineer':employees.join(engineers),
'manager':employees.join(managers),
'boss':employees.join(managers).join(boss),
}, None, 'pjoin')
mapper(Boss, boss,
inherits=manager_mapper,
polymorphic_identity='boss')
a polymorphic fetch "ses.query(Employee).select()" correctly returns
objects of all the classes, and the query "ses.query(Boss).select()"
works fine as well. But while i expected "ses.query(Manager).select()"
to fetch bosses too, an exception with the following error message is
raised::
InvalidRequestError: Given column 'boss.person_id', attached to
table 'boss',
failed to locate a corresponding column from table 'Join object on
employees managers'
I also tried to be explicit about what to join, declaring stuff such::
j1 = employees.join(managers)
person_join = polymorphic_union({
'boss':j1.join(boss),
...
mapper(Boss, boss,
inherits=manager_mapper,
polymorphic_identity='boss',
inherit_condition=boss.c.person_id==j1.c.managers_person_id
)
but eventually anything fails with the same exception.
What i can see is that employees.join(managers) has fields
'employees_person_id' and 'managers_person_id' while the
FromClause.corresponding_column() method looks for a bare 'person_id'
and i don't know how to map them.
Am i doing something obviously wrong or is this something to work on
about inheritance? (currently using SA 3.7)
Thank you,
-- Daniele
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