Hibernate Criteria runtime class
This is my hierarchy:
// Table a
class A {}
// Table(" b
class B extends A {}
// Table my_class
class MyClass {
A a;
}
I want to retrieve all MyClass
objects from database with a relation to B
but not to A
.
B
is a joined-subclass
(extension of the table a
by id).
My idea was something :
Criteria criteria = session.createCriteria(MyClass.class);
criteria.add(Restrictions.eq("a.class", B.class);
But it outputs an error:
could 开发者_开发百科not resolve property: a.class of a.b.MyClass
This is the simplest way I could put it. Bear in mind that the query is a bit more complicated.
Regards.
Udo.
I usually write a DetachedCriteria which selects all B's and filter MyClass where A in AllBs:
DetachedCriteria allBs = DetachedCriteria
.forClass(B.class)
.setProjection( Projections.property("id") );
Criteria criteria = session.createCriteria(MyClass.class)
.add(Subqueries.In("a", allBs);
(There may be errors, I'm not a java programmer.)
Creates something like:
select ...
from MyClass
where A in (select id from A inner join B on ...)
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