Hibernate: request objects by attributes of inherited classes

Question

I am having a problem with Hibernate regarding requests to classes that use inheritance. Basically, I have the following class hierarchy:

@Entity @Table( name = "recording" ) class Recording { ClassA attributeSet; ... } @Entity @Inheritance( strategy = InheritanceType.JOINED ) @Table( name = "classA" ) public class ClassA { String Id; ... } @Entity @Table( name = "ClassB1" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB1 extends ClassA { private Double P1300; private Double P2000; } @Entity @Table( name = "ClassB2" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB2 extends ClassA { private Double P1300; private Double P3000; } 

The hierarchy has already been set this way, and I cannot easily change it. As you can see ClassB1 and ClassB2 inherit from ClassA. Both classes contain a set of attributes that sometimes even have the same name (but I cannot transfer them to ClassA, since there are additional subclasses that do not use them). A record class refers to one instance of one of these classes.

Now my question is: I want to select all the record objects in my database that are related to an instance of ClassB1 or ClassB2, for example. P1300 field == 15.5 (so it can be instances of ClassB1 or ClassB2, since the P1300 attribute is declared in both classes).

What I tried looks something like this:

 Criteria criteria = session.createCriteria(Recording.class); criteria.add( Restrictions.eq( "attributeSet.P1300", new Double(15.5) ) ); criteria.list(); 

But since the P1300 is not an attribute of the ClassA sleep mode, it throws an exception telling me:

 could not resolve property: P1300 of: ClassA 

How can I say that hibernation should look in all subclasses to find the attribute that I want to filter?

Thanks MichaelD

Answer 1

Since the private Double P1300 appears in both subclasses, just pull it up to the parent class.

If there are other ancestors that do not have this property, then such a request does not make much sense - attributeSet may or may not have this property.

Answer 2

I do not have access to a good IDE to verify this, but you must first add and add an alias to your request.

Try adding:

 criteria.createAlias("attributeSet", "attributeSet"); 

I do not think that the problem is related to the hierarchy, but the lack of an alias in your request.