Downcast entities in a join

[Frans]

Hi,

I have a problem similar to the one described at https://www.logicbig.com/tutorials/java-ee-tutorial/jpa/jpql-downcasting-with-treat-operator.html

Basically a master entity (Project) that has a one to many relation with other entities that are defined with joined inheritance (Employee <- FullTimeEmployee, PartTimeEmployee, ContractEmployee)

I'm trying to build a JPA query equivalent to:

SELECT DISTINCT p FROM Project p JOIN TREAT(p.employees AS FullTimeEmployee) e WHERE e.annualSalary > 100000

I tried with the com.querydsl.jpa.JPQLOps.TREAT operator but I can't find a way to make a join based on that.

Any idea?

Thanks!

[Luis Fernando Planella Gonzalez]

You can do it like this :

EntityManager em = ...;
QProject p = QProject.project;
QFullTimeEmployee e = QFullTimeEmployee.fullTimeEmployee;
List<FullTimeEmployee> emps = new JPAQuery<>(em)
    .select(p)
    .distinct()
    .from(p)
    .innerJoin(p.employees, e._super)
    .where(e.annualSalary.gt(100000))
    .fetch();

[Frans]

Works like a charm, thank you!