[SOLVED] Hibernate ignoring discriminator column

Hibernate ignoring discriminator column - always using 'dtype'

I have a strange situation in my SINGLE_TAB inheritance Hibernate config whereby the @DiscriminatorColumn seems to be ignored and the query is always defaulting back to the 'dtype' column. It's like the behaviour I would see when I had not included the annotation at all (the default column name being 'dtype').

Base entity:

@Entity
@Table(name = "post")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(columnDefinition = "post_type", discriminatorType = DiscriminatorType.STRING)
public class Post {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "title")
    private String title;

    @Column(name = "body")
    private String body;

    @NotNull
    @Column(name = "post_type", insertable = false, updatable = false)
    private String postType;

    // other simple columns



    // ommit getters/setters + hashcode etc
}

Subclass entity:

@Entity
@DiscriminatorValue(value = "EVENT")
public class Event extends Post {

    // ommitted basic methods, no extra config

}

I also need access to the discriminator value itself within each object (the postType field). I still have the same behaviour even if I remove it so it doesn't seem to be the cause.

When I try to do a query on the subclass through a JPA repository:

public interface EventRepository extends JpaRepository<Event, Integer> {
    List<Event> findAll();
}

Hibernate generates the query:

select post0_.id as id2_4_, post0_.bodyl as body_bod3_4_, post0_.title as title12_4_ 
from post post0_ 
where post0_.dtype='EVENT'

which of course generates an error as 'dtype' doesn't exist in the table.

The strange thing is that if I use @DiscriminatorFormula("post_type") on the Post entity instead, everything seems to work. It is however slower so I would prefer to use the @DiscriminatorColumn as it should fit my needs exactly.

I am using Hibernate 5.2.10-FINAL and Spring Data JPA 1.11.4 (or generally the latest of hopefully everything).

Any ideas on what could be causing this?

Solution

I'm think you have this problem because you specified wrong parameter of @DiscriminatorColumn anotation, you should use name instead of columnDefinition.