sorry to ride your thread but just to add related question: how can a
reference be seen as its key/id and never the referred instance? turn
off some postprocessing in properties/instrumentedAttr, or not map it
at all?
On Friday 27 June 2008 17:12:21 Paul-Michael Agapow wrote:
> I've got a scenario here that seems as if it would be simple to
> solve, but it baffling me so far. Pointers in the right direction
> would be appreciated.
>
> I have a table of Foo objects, and FooCollection objects. In a
> classic many-to-many, a collection may contain a number of Foos,
> and any given Foo may belong to multiple collections. So far so
> simple. So we create an intermediate table and map accordingly:
>
> class Foo (object):
> ...
>
> class FooCollection (object):
> ...
>
> table_foocollections = Table ('foocollections', mymetadata,
> ...)
>
> table_foo = Table ('foo', mymetadata, ...)
>
> table_foocollections_foo = Table ('foocollection_foo',
> mymetadata,
> Column ('collection_id',
> None,
> ForeignKey ('foocollections.id'),
> primary_key=True
> ),
> Column ('foo_id',
> None,
> ForeignKey ('foo.id'),
> primary_key=True,
> ),
> )
>
> mapper (FooCollection, table_foocollections,
> properties={
> 'members': relation (FooCollection,
> secondary=table_foocollections_foo,
> ),
> },
> )
>
> So when I retrieve or update a FooCollection, "members" has all the
> contained Foos.
>
> But, I have a situation where I don't want FooCollection to
> actually contain the actual Foos, just a list of their keys. That
> is, Foos and FooCollections have to be handled separately.
> Obviously it will involve more paperwork, but how can I make the
> "members" attribute just contain the keys? Is a mapper extension
> required, or is there a simpler way?
>
> p
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