Question: is there any way to get entity class in JPQL query

Question

Hello, I'm using J*dev 11gR1 adn JPA with EclipceLink*.
Let's consider such example
@Entity
@Table(name="ANIMALS")
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class Animal implements Serializable {
@Entity
@Table(name = "CATS")
public class Cat extends Animal implements Serializable{
@Entity
@Table(name = "DOGS")
public class Dog extends Animal implements Serializable{
}I need to build a query which will be translated to something like this SQL query:
SELECT * FROM CATS
UNION ALL
SELECT * FROM DOGS
ORDER BY ...So I need a way to query not all child entities from DB.
P.S. Yes, I know, that I can execute query on panent entity (select a from Animal a order by ...) and then loop throught the result list and delete not needed objects OR I can execute some queries on needed child entities and then merge them into one list and sort it, BUT both ways it will be much slower than generetion of needed SQL query straight to DB.
I know, that in Hibernate's HQL there is a way to build such query with something like this:
select * from Animal a where a.class = Cat or a.class = Dog

Answer 1

In JPA 2.0 which we are implementing right now you will be able to execute queries like:
SELECT a FROM Animal a  WHERE TYPE(a) IN (Cat, Dog)The next draft of the specification contains a section which describes the feature in detail and provides more examples of its use:
4.6.17.4 Entity Type Expressions
An entity type expression can be used to restrict query polymorphism. The TYPE operator returns the
exact type of the argument.I have also been working with some customers on similar capabilities using the current versions of EclipseLink. The examples are documented here:
http://wiki.eclipse.org/EclipseLink/Development/JPA/QueryDownCast
I hope this helps,
Doug