Question

I have following inheritance hierarchy:

Task
  |
SpecificTask
  |
VerySpecificTask

And I’d like to persist it usign single-table inheritance, so I annotated classes:

@Entity
@Table(name="task")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
public class Task 

@Entity
public class SpecificTask extends Task 

@Entity
public class VerySpecificTask extends SpecificTask

When I try to save an object of VerySpecificTask class, I get an error:

Unable to resolve entity name from Class [com.application.task.VerySpecificTask] 
expected instance/subclass of [com.application.task.Task]

What do I wrong? Is it possible to map multi-level inheritance to single table?

EDIT: Here was a lame bug, I’ve resolved quickly, so I deleted it to not mess this question.

Answer 1

OK, I’ve added discriminator column and now it works.
Changed code:

@Entity
@Table(name="task")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(
        name="DTYPE",
        discriminatorType=DiscriminatorType.STRING
    )

@Entity
public class SpecificTask extends Task 

@Entity
public class VerySpecificTask extends SpecificTask

(I’m adding it just to provide an accepted answer — I wouldn’t resolve it without the helpful comments to the question.)