How should I refer to inner enums (defined within an entity) from a JPQL query using Hibernate?

Question

I have an entity class as follows:

package stuff;

@Entity
class Thing {

    @Id
    @GeneratedValue 
    private Long id;

    @Basic
    @Enumerated
    private State state;

    public enum State {
        AWESOME,
        LAME
    }
}

How can I select all Things with state AWESOME using JPQL and Hibernate?

select t from Thing t where t.state=stuff.Thing.State.AWESOME

...gives the error...

org.hibernate.hql.internal.ast.QuerySyntaxException: Invalid path: 'stuff.Thing.State.AWESOME'

Answer 1

Use the following idiom:

select t from Thing t where t.state=stuff.Thing$State.AWESOME

Type$InnerType is Java's naming convention for inner types.

When you try to use dot notation, Hibernate assumes that you're trying to access nested properties, which (properly) fails in this case.