Joining to ClassA.b does not include an automatic upgrade of ClassB to also
load it's joined inheritance table ClassC.This is actually something
SQLAlchemy can't quite do yet unless you hardwired a with_polymorphic onto
your ClassB, which means it would join to ClassC all the time. 0.8 has a new
with_polymorphic() feature which gets closer, but still contains_eager() is not
smart enough to do it yet - this is ticket #1106 related to ticket #2438. May
or not be doable in 0.8 depending on how things go.
The only option for now, short of hardwiring ClassB to be
with_polymorphic-ClassC, is to load ClassB + ClassC separately with
query(ClassB).with_polymorphic(ClassC), using a subqueryload approach, then
affixing them to each parent - see the recipe at
http://www.sqlalchemy.org/trac/wiki/UsageRecipes/DisjointEagerLoading .
On May 31, 2012, at 6:47 AM, Francesco wrote:
Hello everyone,
I have a big problem that alone can not solve.
There are tens of days I try to figure out how to solve this problem.
I created a little test to make you understand better.
http://pastebin.com/hdqR5P6G
I need to know the value of d.CODE with a single query on ClassA.
I need get a list of ClassA object but eager load d.CODE in
polymorphic parent.
Is there anyone who can help me?
Best regards,
Francesco
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