我应该如何使用Hibernate从JPQL查询中引用内部枚举（在实体中定义）？

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.

Answer 2

select t from Thing t where t.state='AWESOME'