在jpql select中指定列会导致转换错误

Question

When I specify columns in my jpql/jpa 2.0 query, ie select p.id, p.lastName, p.firstName from Profile p where p.group = :group I get the following error: [Ljava.lang.Object; cannot be cast to com.profs.ws.Profile... [Ljava.lang.Object; cannot be cast to com.profs.ws.Profile... Anyone know how to resolve this casting issue?

The Profile entity class itself has properties of the following types: String, int, and Collection . The properties I'm selecting in the query are either of the type String or int .

Answer 1

When you specify properties of an object, JPA returns the list of Object[] . You can cast the return value to List<Object[] instead of List<Profile> to avoid the ClassCastException . If you are using Hibernate as JPA provider, you can map the select clause to a new object. See select clause documentation for details.