Hello,
Is it possible in OJB to do these two things?
1. Create a Query representing the intersection of two other
Queries (intersection to be executed in the database)
2. Use Criteria.addEqualToField() within a subquery where the named
field actually comes from an object in a parent or grandparent query.
Thanks,
Scott Howlett
PS - To explain a bit more, here's a simplified version of what
I'm trying to do.
Represent access privileges between users and documents:
- Users can be in groups, documents can also be in groups
- Entitlement is specified either directly (user_id <-> document_id)
or indirectly (via user or group id).
- id values are globally unique.
tables are like this (just showing the primary key columns):
user { id }
user_group { id }
user_group_membership { user_id, user_group_id }
doc { id }
doc_group { id }
doc_group_membership { doc_id, doc_group_id }
entitlement { user_or_user_group_id, doc_or_doc_group_id }
Given a particular user with id <USER_ID>, accessible documents are
those with a non-null intersection of (user / user group entitlements)
and (doc / doc group entitlements) (pseudo-SQL):
select * from doc where
(select count (*) from (
(select * from entitlement where
(user_or_user_group_id = <USER_ID>) or
(user_or_user_group_id in
(select user_group_id from user_group_membership where
user_id = <USER_ID>)))
intersect
(select * from entitlement where
(doc_or_doc_group_id = id) or
(doc_or_doc_group_id in
(select doc_group_id from doc_group_membership where
doc_id = id)))
)) > 0
My question #1 is because of the 'intersect' statement.
My question #2 is because in the second sub-sub-query, I'm
twice referring to the document field 'id' which comes
from the top-level query 'select * from doc'.
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